Teradyne (TER) 10-Q 7 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Apr. 04, 2021	Apr. 30, 2021
Cover [Abstract]
Amendment Flag	false
Document Type	10-Q
Document Fiscal Year Focus	2021
Entity Central Index Key	0000097210
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Document Period End Date	Apr. 4, 2021
Entity Registrant Name	TERADYNE, INC
Entity Filer Category	Large Accelerated Filer
Trading Symbol	TER
Document Quarterly 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		166,266,321

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Apr. 04, 2021		Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 831,149		$ 914,121
Marketable securities	478,293		522,280
Accounts receivable, less allowance for credit losses of $1,939 and $2,034 at April 4, 2021 and December 31, 2020, respectively	581,509		497,506
Inventories, net	262,474		222,189
Prepayments and other current assets	347,678		259,338
Total current assets	2,501,103		2,415,434
Property, plant and equipment, net	402,465		394,800
Operating lease right-of-use assets, net	51,516		54,569
Marketable securities	115,620		117,980
Deferred tax assets	92,365		87,913
Retirement plans assets	17,255		17,468
Other assets	8,942		9,384
Acquired intangible assets, net	92,850		100,939
Goodwill	437,601		453,859
Total assets	3,719,717	[1]	3,652,346
Current liabilities:
Accounts payable	177,473		133,663
Accrued employees' compensation and withholdings	138,238		220,321
Deferred revenue and customer advances	144,812		134,662
Other accrued liabilities	105,238		77,581
Operating lease liabilities	19,675		20,573
Income taxes payable	90,349		80,728
Current debt	11,057		33,343
Total current liabilities	686,842		700,871
Retirement plans liabilities	152,508		151,140
Long-term deferred revenue and customer advances	55,138		58,359
Long-term contingent consideration			7,227
Long-term other accrued liabilities	18,982		19,352
Deferred tax liabilities	9,606		10,821
Long-term operating lease liabilities	39,048		42,073
Long-term incomes taxes payable	74,930		74,930
Debt	356,877		376,768
Total liabilities	1,393,931		1,441,541
Commitments and contingencies (See Note Q)
Mezzanine equity:
Convertible common shares	1,233		3,787
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized; 166,419 and 166,123 shares issued and outstanding at April 4, 2021 and December 31, 2020, respectively	20,802		20,765
Additional paid-in capital	1,765,971		1,765,323
Accumulated other comprehensive income	8,677		33,516
Retained earnings	529,103		387,414
Total shareholders' equity	2,324,553		2,207,018
Total liabilities, convertible common shares and shareholders' equity	$ 3,719,717		$ 3,652,346
[1]	Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Accounts receivable, less allowance for credit losses	$ 1,939	$ 2,034
Common stock, par value	$ 0.125	$ 0.125
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	166,419	166,123
Common stock, shares outstanding	166,419	166,123

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Revenues:
Total revenues	[1]	$ 781,606	$ 704,355
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		319,988	298,805
Gross profit		461,618	405,550
Operating expenses:
Selling and administrative		129,797	111,388
Engineering and development		100,402	85,159
Acquired intangible assets amortization		5,536	9,891
Restructuring and other		(7,130)	(7,606)
Total operating expenses		228,605	198,832
Income from operations		233,013	206,718
Non-operating (income) expense:
Interest income		(808)	(2,751)
Interest expense		6,004	5,551
Other (income) expense, net		3,824	6,849
Income before income taxes		223,993	197,069
Income tax provision		18,481	20,878
Net income		$ 205,512	$ 176,191
Net income per common share:
Basic		$ 1.23	$ 1.06
Diluted		$ 1.09	$ 0.97
Weighted average common shares—basic		166,491	166,589
Weighted average common shares—diluted		187,740	180,736
Cash dividend declared per common share		$ 0.10	$ 0.10
Product [Member]
Revenues:
Total revenues		$ 660,508	$ 610,906
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		267,784	259,996
Service [Member]
Revenues:
Total revenues		121,098	93,449
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)		$ 52,204	$ 38,809
[1]	Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.”

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Net income	$ 205,512	$ 176,191
Other comprehensive income, net of tax:
Foreign currency translation adjustment, net of tax of $0, $0	(21,123)	(8,779)
Available-for-sale marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(908), $187, respectively	(3,270)	1,037
Less: Reclassification adjustment for gains included in net income, net of tax of $(123), $(145), respectively	(444)	(515)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total	(3,714)	522
Defined benefit post-retirement plan:
Amortization of prior service credit, net of tax of $0, $0, respectively	(2)	(2)
Other comprehensive loss	(24,839)	(8,259)
Comprehensive income	$ 180,673	$ 167,932

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Foreign currency translation adjustments, tax	$ 0	$ 0
Unrealized (losses) gains on marketable securities arising during period, net of tax	908	187
Reclassification adjustment for gains included in net income, net of tax	123	145
Amortization of prior service credit, net of tax	$ 0	$ 0

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Common Shares	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
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	(9,936)		$ 109	(10,045)
Net issuance of common stock under stock-based plans (in shares)			872
Stock-based compensation expense	11,283			11,283
Repurchase of common stock	$ (82,065)		$ (168)			(81,897)
Repurchase of common stock (in shares)	1,300		(1,344)
Cash dividends	$ (16,699)					(16,699)
Net income	176,191					176,191
Other comprehensive loss	(8,259)				(8,259)
Balance at Mar. 29, 2020	1,550,673		$ 20,742	1,721,367	(27,113)	(164,323)
Balance, Shares at Mar. 29, 2020			165,938
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
Net issuance of common stock under stock-based plans	(13,987)		$ 84	(14,071)
Net issuance of common stock under stock-based plans (in shares)			670
Convertible common shares	2,554			2,554
Exercise of convertible notes hedge call options	(158,876)		$ (153)	(158,723)
Stock-based compensation expense	13,359			13,359
Repurchase of common stock	$ (47,188)		$ (47)			(47,141)
Repurchase of common stock (in shares)	400		(374)
Cash dividends	$ (16,682)					(16,682)
Net income	205,512					205,512
Other comprehensive loss	(24,839)				(24,839)
Balance at Apr. 04, 2021	2,324,553		$ 20,802	1,765,971	$ 8,677	$ 529,103
Balance, Shares at Apr. 04, 2021		1,233	166,419
Convertible common shares (in shares)		(2,554)	1,222
Settlements of convertible notes	$ 157,682		$ 153	$ 157,529
Settlements of convertible notes (in shares)		(2,554)	1,222
Exercise of convertible notes hedge call options (in shares)			(1,222)

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Common Stock, Dividends, Per Share, Cash Paid	$ 0.10	$ 0.10

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Cash flows from operating activities:
Net income	$ 205,512	$ 176,191
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Depreciation	23,910	18,489
Stock-based compensation	12,232	10,460
Amortization	9,822	13,391
Loss on convertible debt conversion	4,069
Provision for excess and obsolete inventory	2,285	4,057
Contingent consideration adjustment	(7,227)	(10,020)
(Gains) losses on investments	(2,491)	4,657
Deferred taxes	(1,057)	(1,825)
Other	200	503
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(87,512)	(126,779)
Inventories	(35,870)	15,818
Prepayments and other assets	(86,131)	(39,620)
Accounts payable and other liabilities	(10,571)	(35,323)
Deferred revenue and customer advances	7,952	(913)
Retirement plans contributions	(1,925)	(1,262)
Income taxes	4,941	15,278
Net cash provided by operating activities	38,139	43,102
Cash flows from investing activities:
Purchases of property, plant and equipment	(39,250)	(36,700)
Purchases of marketable securities	(211,604)	(187,119)
Proceeds from maturities of marketable securities	194,228	98,457
Proceeds from sales of marketable securities	61,293	15,005
Acquisition of businesses, net of cash acquired		149
Net cash provided by (used for) investing activities	4,667	(110,208)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	17,144	12,752
Payments of convertible debt principal	(51,275)
Repurchase of common stock	(45,188)	(79,039)
Dividend payments	(16,667)	(16,686)
Payments related to net settlement of employee stock compensation awards	(30,675)	(22,070)
Payments of contingent consideration		(8,852)
Net cash used for financing activities	(126,661)	(113,895)
Effects of exchange rate changes on cash and cash equivalents	883	571
Decrease in cash and cash equivalents	(82,972)	(180,430)
Cash and cash equivalents at beginning of period	914,121	773,924
Cash and cash equivalents at end of period	831,149	593,494
Non-cash investing activities:
Capital expenditures incurred but not yet paid	$ 3,840	$ 5,357

The Company

The Company	3 Months Ended
	Apr. 04, 2021
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.

Accounting Policies

Accounting Policies	3 Months Ended
	Apr. 04, 2021
Accounting Policies	B. ACCOUNTING POLICIES Basis of Presentation The consolidated interim financial statements include the accounts of Teradyne and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair statement of such interim financial statements. Certain prior year amounts were reclassified to conform to the current year presentation. The December 31, 2020 condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by United States of America generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K, Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent liabilities. On an on-going COVID-19 10-Q.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	3 Months Ended
	Apr. 04, 2021
Recently Issued Accounting Pronouncements	C. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS In August 2020, the FASB issued ASU 2020-06 if-converted

Revenue

Revenue	3 Months Ended
	Apr. 04, 2021
Revenue from Contract with Customer [Abstract]
Revenue	D. 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 System on-a-Chip Memory System Test Universal Mobile AutoGuide Wireless Test Corporate and Other Total (in thousands) For the Three Months Ended April 4, 2021 (1) Timing of Revenue Recognition Point in Time $ 364,190 $ 101,892 $ 119,314 $ 64,007 $ 14,064 $ (120 ) $ 37,880 $ (143 ) $ 701,084 Over Time 56,040 5,941 13,523 1,594 67 339 3,018 — 80,522 Total $ 420,230 $ 107,833 $ 132,837 $ 65,601 $ 14,131 $ 219 $ 40,898 $ (143 ) $ 781,606 Geographical Market Asia Pacific $ 387,236 $ 104,049 $ 99,520 $ 17,833 $ 3,447 $ — $ 33,532 $ — $ 645,617 Americas 20,779 3,420 27,659 18,153 5,153 219 5,769 (143 ) 81,010 Europe, Middle East and Africa 12,215 364 5,658 29,615 5,531 — 1,597 — 54,980 Total $ 420,230 $ 107,833 $ 132,837 $ 65,601 $ 14,131 $ 219 $ 40,898 $ (143 ) $ 781,606 For the Three Months Ended March 29, 2020 (1) Timing of Revenue Recognition Point in Time $ 348,044 $ 79,398 $ 100,712 $ 47,502 $ 9,097 $ 1,124 $ 41,056 $ — $ 626,933 Over Time 52,095 4,952 15,364 2,195 41 346 2,429 — 77,422 Total $ 400,139 $ 84,350 $ 116,076 $ 49,697 $ 9,138 $ 1,470 $ 43,485 $ — $ 704,355 Geographical Market Asia Pacific $ 362,732 $ 76,110 $ 80,017 $ 10,917 $ 1,593 $ — $ 37,805 $ — $ 569,174 Americas 17,386 6,896 28,291 14,743 3,465 1,470 4,688 — 76,939 Europe, Middle East and Africa 20,021 1,344 7,768 24,037 4,080 — 992 — 58,242 Total $ 400,139 $ 84,350 $ 116,076 $ 49,697 $ 9,138 $ 1,470 $ 43,485 $ — $ 704,355 (1) Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.” Contract Balances For the three months ended April 4, 2021 and March 29, 2020, Teradyne recognized $27.8 million and $39.5 million, respectively, that was previously 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 April 4, 2021, Teradyne has $1,456.0 million of unsatisfied performance obligations. Teradyne expects to recognize 95% of the remaining performance obligations in the next 12 months, 4% in 1-3 Accounts Receivable Teradyne sells certain trade accounts receivables on a non-recourse

Inventories

Inventories	3 Months Ended
	Apr. 04, 2021
Inventories	E. INVENTORIES Inventories, net consisted of the following at April 4, 2021 and December 31, 2020: April 4, December 31, 2021 2020 (in thousands) Raw material $ 117,552 $ 114,133 Work-in-process 32,772 25,408 Finished goods 112,150 82,648 $ 262,474 $ 222,189 Inventory reserves at April 4, 2021 and December 31, 2020 were $107.8 million and $110.6 million, respectively.

Financial Instruments

Financial Instruments	3 Months Ended
	Apr. 04, 2021
Financial Instruments	F. FINANCIAL INSTRUMENTS Cash Equivalents Teradyne considers all highly liquid investments with maturities of three months or less at the date of acquisition to be cash equivalents. Marketable Securities Teradyne’s available-for-sale During the three months ended April 4, 2021 and March 29, 2020, there were no transfers in or out of Level 1, Level 2, or Level 3 financial instruments. Realized gains recorded in the three months ended April 4, 2021 and March 29, 2020 were $1.2 million and $1.4 million, respectively. Realized losses recorded in the three months ended March 29, 2020 were $0.1 million. Realized gains and losses are included in other (income) expense, net. Unrealized gains on equity securities recorded in the three months ended April 4, 2021, were $1.4 million. Unrealized losses on equity securities recorded in the three months ended March 29, 2020 were $6.0 million. Unrealized gains and losses on equity securities are included in other (income) expense, net. Unrealized gains and losses on available-for-sale The cost of securities sold is based on average cost. The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of April 4, 2021 and December 31, 2020.​​​​​​​ April 4, 2021 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 $ 417,888 $ — $ 417,888 Cash equivalents 386,694 26,567 — 413,261 Available-for-sale Commercial paper — 306,715 — 306,715 U.S. Treasury securities — 155,190 — 155,190 Corporate debt securities — 83,372 — 83,372 Debt mutual funds 9,288 — — 9,288 U.S. government agency securities — 4,612 — 4,612 Certificates of deposit and time deposits — 966 — 966 Non-U.S. — 619 — 619 Equity securities: Mutual funds 33,151 — — 33,151 $ 847,021 $ 578,041 $ — $ 1,425,062 Derivative assets — 16 — 16 Total $ 847,021 $ 578,057 $ — $ 1,425,078 Liabilities Derivative liabilities $ — $ 393 $ — $ 393 Total $ — $ 393 $ — $ 393 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 804,582 $ 26,567 $ — $ 831,149 Marketable securities — 478,293 — 478,293 Long-term marketable securities 42,439 73,181 — 115,620 Prepayments and other current assets — 16 — 16 Total $ 847,021 $ 578,057 $ — $ 1,425,078 Liabilities Other current liabilities $ — $ 393 $ — $ 393 Total $ — $ 393 $ — $ 393 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 — 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. — 625 — 625 Equity securities: Equity mutual funds 29,420 — — 29,420 $ 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 accrued liabilities $ — $ 504 $ — $ 504 Long-term contingent consideration — — 7,227 7,227 Total $ — $ 504 $ 7,227 $ 7,731 Changes in the fair value of Level 3 contingent consideration for the three months ended April 4, 2021, and March 29, 2020 were as follows: For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 7,227 $ 39,705 Fair value adjustment (a)(b) (7,227 ) (10,020 ) Foreign currency impact — (361 ) Payments (c) — (8,852 ) Balance at end of period $ — $ 20,472 (a) In the three months ended April 4, 2021, the fair value of contingent consideration for the earn-outs in connection with the acquisition of AutoGuide was reduced to zero, which resulted in a benefit of $7.2 million, primarily due to a decrease in forecasted revenues and earnings before interest and taxes. As of April 4, 2021, the maximum amount of contingent consideration that could be paid in connection with the acquisition of AutoGuide is $100.2 million. The remaining earn-out earn-out non-compliance earn-out non-compliance. (b) In the three months ended March 29, 2020, the fair value of contingent consideration for the earn-outs in connection with the acquisitions of Mobile Industrial Robots Aps (“MiR”) and AutoGuide decreased by $2.9 million and $7.1 million, respectively, due to lower forecasts. (c) In the three months ended March 29, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out The carrying amounts and fair values of Teradyne’s financial instruments at April 4, 2021 and December 31, 2020 were as follows: April 4, 2021 December 31, 2020 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 831,149 $ 831,149 $ 914,121 $ 914,121 Marketable securities 593,913 593,913 640,260 640,260 Derivative assets 16 16 95 95 Liabilities Contingent consideration — — 7,227 7,227 Derivative liabilities 393 393 504 504 Convertible debt (1) 367,934 1,664,667 410,111 1,739,553 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note, which includes the equity conversion features. The fair values of accounts receivable, net and accounts payable approximate the carrying value due to the short-term nature of these instruments. The following table summarizes the composition of available-for-sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Commercial paper $ 306,707 $ 8 $ — $ 306,715 $ 13,996 U.S. Treasury securities 155,337 644 (791 ) 155,190 24,492 Corporate debt securities 79,190 4,340 (158 ) 83,372 25,553 Debt mutual funds 9,242 46 — 9,288 — U.S. government agency securities 4,581 34 (3 ) 4,612 1,413 Certificates of deposit and time deposits 966 — — 966 — Non-U.S. 619 — — 619 — $ 556,642 $ 5,072 $ (952 ) $ 560,762 $ 65,454 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 478,221 $ 95 $ (23 ) $ 478,293 $ 47,468 Long-term marketable securities 78,421 4,977 (929 ) 82,469 17,986 $ 556,642 $ 5,072 $ (952 ) $ 560,762 $ 65,454 The following table summarizes the composition of 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. 625 — — 625 — $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market 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 As of April 4, 2021 and December 31, 2020, the fair market value of investments with unrealized losses less than one year totaled $65.5 million and $70.4 million, respectively. Teradyne reviews its investments to identify and evaluate investments that have an indication of possible impairment. Based on this review, Teradyne determined that the unrealized losses related to these investments at April 4, 2021 and December 31, 2020 were not other than temporary. The contractual maturities of investments in available-for-sale April 4, 2021 Cost Fair Market Value (in thousands) Due within one year $ 478,221 $ 478,293 Due after 1 year through 5 years 28,597 29,038 Due after 5 years through 10 years 6,103 6,484 Due after 10 years 34,479 37,659 Total $ 547,400 $ 551,474 Contractual maturities of investments in available-for-sale . Derivatives Teradyne conducts business in a number of foreign countries, with certain transactions denominated in local currencies. The purpose of Teradyne’s foreign currency management is to minimize the effect of exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities. Teradyne does not use derivative financial instruments for trading or speculative purposes. To minimize the effect of exchange rate fluctuations associated with the remeasurement of monetary assets and liabilities denominated in foreign currencies, Teradyne enters into foreign currency forward contracts. The change in fair value of these derivatives is recorded directly in earnings and is used to offset the change in value of monetary assets and liabilities denominated in foreign currencies. The notional amount of foreign currency forward contracts at April 4, 2021 and December 31, 2020 was $156.8 million and $152.9 million, respectively. Gains and losses on foreign currency forward contracts and foreign currency remeasurement gains and losses on monetary assets and liabilities are included in other (income) expense, net. The following table summarizes the fair value of derivative instruments as of April 4, 2021 and December 31, 2020: Balance Sheet Location April 4, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 16 $ 95 Foreign exchange contracts Other current liabilities (393 ) (504 ) Total derivatives $ (377 ) $ (409 ) The following table summarizes the effect of derivative instruments recognized in the statement of operations for the three months ended April 4, 2021 and March 29, 2020: Location of Losses Recognized in Statement of Operations For the Three Months Ended April 4, March 29, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 2,118 $ 4,011 (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 three months ended April 4, 2021 and March 29, 2020, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $0.2 million and $2.0 million, respectively. See Note G: “Debt” regarding derivatives related to the convertible senior notes.

Debt

Debt	3 Months Ended
	Apr. 04, 2021
Debt	G. 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 from December 12, 2016 at a rate of 1.25 June 15 quarter beginning after March 31, 2017 (and only during such calendar quarter), if the closing sale price of Teradyne’s common stock, for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price (as defined in the Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the closing sale price of the Teradyne’s common stock and the conversion rate on each such trading day; and (3) upon the occurrence of specified corporate events. On or after September 15, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. Teradyne may satisfy its conversion obligation by paying or delivering cash, shares of its common stock or a combination of cash and shares of its common stock, at Teradyne’s election. As of April 4, 2021, the conversion price was approximately $31.55 per share of Teradyne’s common stock. The conversion rate is subject to adjustment under certain circumstances. As of May 7, 2021, thirty-six 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 $31.55. The Note Hedge Transactions cover, subject to customary anti-dilution adjustments, approximately 13.0 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 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,” fixed-for-fixed Teradyne assessed whether the convertible note hedge should be classified as equity under ASC 815-40. 815-40 Teradyne analyzed the Warrant Transactions under ASC 815-40, “Derivatives and Hedging—Contracts in Entity’s Own Equity,” paid-in The provisions of ASC 470-20, Debt with Conversion and Other Options, 470-20 are The below tables represent the key components of Teradyne’s convertible senior notes: April 4, 2021 December 31, 2020 (in thousands) Debt principal $ 408,695 $ 459,971 Unamortized discount 40,761 49,860 Net carrying amount of convertible debt $ 367,934 $ 410,111 Reported as follows: April 4, 2021 December 31, 2020 (in thousands) Current debt $ 11,057 $ 33,343 Long-term debt 356,877 376,768 Net carrying amount of convertible debt $ 367,934 $ 410,111 For the Three Months April 4, 2021 March 29, 2020 (in thousands) Contractual interest expense on the coupon $ 1,239 $ 1,438 Amortization of the discount component and debt issue fees recognized as interest expense 3,836 3,792 Total interest expense on the convertible debt $ 5,075 $ 5,230 As of April 4, 2021, the remaining unamortized discount was $40.8 million, which will be amortized over 2.7 years using the effective interest rate method. The carrying amount of the equity component was $100.8 million. As of April 4, 2021, the conversion price was approximately $31.55 per share and the if-converted During the three months ended April 4, 2021, certain debt holders elected to convert $51.3 million of debt principal. The conversion of the debt was settled in cash for principal amount and in shares for the excess of conversion value over principal amount. The million shares issued to the debt holders were received from exercising the convertible notes hedge call options. Additional conversions of approximately m Revolving Credit Facility On May 1, 2020, Teradyne entered into a credit agreement (the “Credit Agreement”) with Truist Bank, as administrative agent and collateral agent, and the lenders party thereto. The Credit Agreement provides for a three-year, senior secured revolving credit facility of $400.0 million (the “Credit Facility”). The Credit Agreement further provides that, subject to customary conditions, Teradyne may seek to obtain from existing or new lenders incremental commitments under the Credit Facility in an aggregate principal amount not to exceed $150.0 million. Proceeds from the Credit Facility may be used for general corporate purposes and working capital. Teradyne incurred $3.5 million in costs related to the revolving credit facility. These costs are being amortized over the three-year term of the revolving credit facility and are included in interest expense in the statement of operations. As of May 7, 2021, Teradyne has not borrowed any funds under the Credit Facility. The interest rates applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.50% 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 May 7, 2021, Teradyne was in compliance with all covenants.

Prepayments

Prepayments	3 Months Ended
	Apr. 04, 2021
Prepayments [Abstract]
Prepayments	H. PREPAYMENTS Prepayments consist of the following and are included in prepayments and other assets on the balance sheet: April 4, December 31, 2021 2020 (in thousands) Contract manufacturer and supplier prepayments $ 291,175 $ 212,286 Prepaid maintenance and other services 15,521 13,116 Prepaid taxes 13,814 9,361 Other prepayments 16,072 15,329 Total prepayments $ 336,582 $ 250,092

Deferred Revenue and Customer A

Deferred Revenue and Customer Advances	3 Months Ended
	Apr. 04, 2021
Deferred Revenue and Customer Advances	I. DEFERRED REVENUE AND CUSTOMER ADVANCES Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet: April 4, December 31, 2021 2020 (in thousands) Maintenance, service and training $ 78,321 $ 77,654 Customer advances, undelivered elements and other 67,721 63,438 Extended warranty 53,908 51,929 Total deferred revenue and customer advances $ 199,950 $ 193,021

Product Warranty

Product Warranty	3 Months Ended
	Apr. 04, 2021
Product Warranties Disclosures [Abstract]
Product Warranty	J. PRODUCT WARRANTY Teradyne generally provides a one-year For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 16,633 $ 8,996 Accruals for warranties issued during the period 11,881 5,066 Accruals related to pre-existing 447 1,056 Settlements made during the period (5,068 ) (4,147 ) Balance at end of period $ 23,893 $ 10,971 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. For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 51,929 $ 30,677 Deferral of new extended warranty revenue 7,517 7,600 Recognition of extended warranty deferred revenue (5,538 ) (4,774 ) Balance at end of period $ 53,908 $ 33,503

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Apr. 04, 2021
Stock-Based Compensation	K. STOCK-BASED COMPENSATION Under Teradyne’s stock compensation plans, Teradyne grants service-based restricted stock units, performance-based restricted stock units and stock options, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Service-based restricted stock unit awards granted to employees vest in equal annual installments over four years. Restricted stock unit awards granted to non-employee one-year 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-year TSR performance is measured against the New York Stock Exchange (“NYSE”) Composite Index. The final number of TSR PRSUs that vest will vary based upon the level of performance achieved from 0% to 200% of the target shares. 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 cumulative non-GAAP Non-GAAP non-cash non-recurring 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 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 the three months ended April 4, 2021 and March 29, 2020, Teradyne granted 0.3 million and 0.4 million of service-based restricted stock unit awards to employees at a weighted average grant date fair value of $112.55 and $70.98, respectively. During the three months ended April 4, 2021 and March 29, 2020, Teradyne granted 0.1 million of PBIT PRSUs with a grant date fair value of $112.28 and $70.94, respectively. During the three months ended April 4, 2021 and March 29, 2020, Teradyne granted 0.1 million of TSR PRSUs, with a grant date fair value of $125.02 and $89.93, respectively. The fair value was estimated using the Monte Carlo simulation model with the following assumptions: For the Three Months Ended April 4, March 29, 2021 2020 Risk-free interest rate 0.2 % 1.5 % Teradyne volatility-historical 43.9 % 34.9 % NYSE Composite Index volatility-historical 22.9 % 11.4 % Dividend yield 0.4 % 0.6 % Expected volatility was based on the historical volatility of Teradyne’s stock and the NYSE Composite Index over the most recent three-year period. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.40 per share divided by Teradyne’s stock price on the grant date of $113.48 for the 2021 grant and an estimated annual dividend amount of $0.40 per share divided by Teradyne’s stock price on the grant date of $72.10 for the 2020 grant. During the three months ended April 4, 2021 and March 29, 2020, Teradyne granted 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $36.60 and $20.67, respectively. The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended April 4, March 29, 2021 2020 Expected life (years) 5.0 5.0 Risk-free interest rate 0.4 % 1.6 % Volatility-historical 37.8 % 31.6 % Dividend yield 0.4 % 0.6 % 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 $113.48 for the 2021 grant and an estimated annual dividend amount of $0.40 per share divided by Teradyne’s stock price on the grant date of $72.10 for the 2020 grant.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Apr. 04, 2021
Accumulated Other Comprehensive Income (Loss)	L. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Changes in accumulated other comprehensive income (loss), which are presented net of tax, consist of the following: Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Service Credit Total (in thousands) Three Months Ended April 4, 2021 Balance at December 31, 2020, net of tax of $0, $1,910, $(1,126), respectively $ 25,389 $ 6,954 $ 1,173 $ 33,516 Other comprehensive loss before reclassifications, net of tax of $0, $(908), $0, respectively (21,123 ) (3,270 ) — (24,393 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(123), $0, respectively — (444 ) (2 ) (446 ) Net current period other comprehensive loss, net of tax of $0, $(1,031), $0, respectively (21,123 ) (3,714 ) (2 ) (24,839 ) Balance at April 4, 2021, net of tax of $0, $879, $(1,126), respectively $ 4,266 $ 3,240 $ 1,171 $ 8,677 Three Months Ended March 29, 2020 Balance at December 31, 2019, net of tax of $0, $946, $(1,124), respectively $ (23,514 ) $ 3,480 $ 1,180 $ (18,854 ) Other comprehensive (loss) income before reclassifications, net of tax of $0, $187, $0, respectively (8,779 ) 1,037 — (7,742 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(145), $0, respectively — (515 ) (2 ) (517 ) Net current period other comprehensive (loss) income, net of tax of $0, $42, $0, respectively (8,779 ) 522 (2 ) (8,259 ) Balance at March 29, 2020, net of tax of $0, $988, $(1,124), respectively $ (32,293 ) $ 4,002 $ 1,178 $ (27,113 ) Reclassifications out of accumulated other comprehensive income (loss) to the statement of operations for the three months ended April 4, 2021 and March 29, 2020 were as follows: Details about Accumulated Other Comprehensive Income Components For the Three Months Ended Affected Line Item in the Statements of Operations April 4, March 29, 2021 2020 (in thousands) Available-for-sale Unrealized gains, net of tax of $123, $145, respectively $ 444 $ 515 Other (income) Defined benefit postretirement plan: Amortization of prior service credit, net of tax of $0, $0, respectively 2 2 (a) Total reclassifications, net of tax of $123, $145, respectively $ 446 $ 517 Net income (a) The amortization of prior service credit is included in the computation of net periodic postretirement benefit cost. See Note P: “Retirement Plans.”

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	3 Months Ended
	Apr. 04, 2021
Goodwill and Intangible Assets	M. GOODWILL AND ACQUIRED INTANGIBLE ASSETS Goodwill Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “Intangibles—Goodwill and Other” The changes in the carrying amount of goodwill by reportable segments for the three months ended April 4, 2021, were as follows: Industrial Automation System Test Wireless Test Semiconductor Test Total (in thousands) Balance at December 31, 2020 Goodwill $ 433,752 $ 158,699 $ 361,819 $ 262,155 $ 1,216,425 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) 433,752 10,516 7,976 1,615 453,859 Foreign currency translation adjustment (16,156 ) — — (102 ) (16,258 ) Balance at April 4, 2021 Goodwill 417,596 158,699 361,819 262,053 1,200,167 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) $ 417,596 $ 10,516 $ 7,976 $ 1,513 $ 437,601 Intangible Assets Teradyne reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful lives of these assets are no longer appropriate. Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet: Gross Carrying Amount Accumulated Amortization Foreign Currency Net Carrying Amount (in thousands) Balance at April 4, 2021 Developed technology $ 272,547 $ (213,459 ) $ (3,198 ) $ 55,890 Customer relationships 57,739 (47,209 ) 150 10,680 Tradenames and trademarks 70,120 (43,716 ) (124 ) 26,280 Total intangible assets $ 400,406 $ (304,384 ) $ (3,172 ) $ 92,850 Balance, December 31, 2020 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 Aggregate intangible asset amortization expense for the three months ended April 4, 2021 and March 29, 2020 was $5.5 million and $9.9 million, respectively. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2021 (remainder) 15,896 2022 20,423 2023 19,941 2024 19,634 2025 11,699 Thereafter 5,257

Net Income Per Common Share

Net Income Per Common Share	3 Months Ended
	Apr. 04, 2021
Net Income per Common Share	N. NET INCOME PER COMMON SHARE The following table sets forth the computation of basic and diluted net income per common share: For the Three Months Ended April 4, 2021 March 29, 2020 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 205,512 $ 176,191 Weighted average common shares-basic 166,491 166,589 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 10,310 7,333 Convertible note hedge warrant shares (2) 9,429 5,492 Restricted stock units 1,395 1,163 Stock options 108 134 Employee stock purchase plan 7 25 Dilutive potential common shares 21,249 14,147 Weighted average common shares-diluted 187,740 180,736 Net income per common share-basic $ 1.23 $ 1.06 Net income per common share-diluted $ 1.09 $ 0.97 (1) Incremental shares from assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.55, multiplied by 13.8 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 $39.59, multiplied by 13.8 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. The computation of diluted net income per common share for the three months ended March 29, 2020 excludes the effect of the potential vesting of 0.3 million restricted stock units because the effect would have been anti-dilutive.

Restructuring and Other

Restructuring and Other	3 Months Ended
	Apr. 04, 2021
Restructuring and Related Activities [Abstract]
Restructuring and Other	O. RESTRUCTURING AND OTHER During the three months ended April 4, 2021, Teradyne recorded a gain of $7.2 million for the decrease in the fair value of the AutoGuide contingent consideration liability, a gain of $0.2 million for the decrease in acquisition related compensation liability, partially offset by $0.2 million of severance charges primarily in Industrial Automation. During the three months ended March 29, 2020, Teradyne recorded a gain of $10.0 million 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.

Retirement Plans

Retirement Plans	3 Months Ended
	Apr. 04, 2021
Retirement Plans	P. RETIREMENT PLANS ASC 715, “Compensation—Retirement Benefits” Defined Benefit Pension Plans Teradyne has defined benefit pension plans covering a portion of domestic employees and employees of certain non-U.S. In the three months ended April 4, 2021, Teradyne contributed $0.8 million to the U.S. supplemental executive defined benefit pension plan and $0.3 million to certain qualified pension plans for non-U.S. For the three months ended April 4, 2021 and March 29, 2020, Teradyne’s net periodic pension cost was comprised of the following: For the Three Months Ended April 4, 2021 March 29, 2020 United States Foreign United States Foreign (in thousands) Service cost $ 453 $ 243 $ 433 $ 201 Interest cost 1,100 87 1,522 115 Expected return on plan assets (936 ) (16 ) (1,233 ) (15 ) Total net periodic pension cost $ 617 $ 314 $ 722 $ 301 Postretirement Benefit Plan In addition to receiving pension benefits, Teradyne employees in the United States who meet early retirement eligibility requirements as of their termination dates may participate in Teradyne’s Welfare Plan, which includes medical and dental benefits up to age 65. Death benefits provide a fixed sum to retirees’ survivors and are available to all retirees. Substantially all of Teradyne’s current U.S. employees could become eligible for these benefits, and the existing benefit obligation relates primarily to those employees. For the three months ended April 4, 2021 and March 29, 2020, Teradyne’s net periodic postretirement benefit cost was comprised of the following: For the Three Months Ended April 4, March 29, (in thousands) Service cost $ 16 $ 11 Interest cost 44 62 Amortization of prior service credit (2 ) (2 ) Total net periodic postretirement benefit cost $ 58 $ 71

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Apr. 04, 2021
Commitments and Contingencies	Q. COMMITMENTS AND CONTINGENCIES Purchase Commitments As of April 4, 2021, Teradyne had entered into purchase commitments for certain components and materials. The purchase commitments covered by the agreements aggregate to approximately $680.7 million, of which $666.8 million is for less than one year. Legal Claims Teradyne is subject to various legal proceedings and claims which have arisen in the ordinary course of business 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. On March 8, 2021, Industrial Automation LLC submitted a demand for arbitration against Teradyne and AutoGuide in Wilmington, Delaware alleging that Teradyne and AutoGuide breached certain provisions of the Membership Interests Purchase Agreement (the “Purchase Agreement”), dated as of October 18, 2019, among Industrial Automation LLC, Teradyne and AutoGuide. The arbitration demand seeks full acceleration of the maximum earnout amount payable under the Purchase Agreement, or $106,875,000, for the alleged breach of the earnout provisions of the Purchase Agreement. On March 26, 2021, Teradyne and AutoGuide filed an answer denying that Teradyne and AutoGuide breached any provisions of the Purchase Agreement. A preliminary hearing will be scheduled once the arbitration tribunal is convened. While it is not possible at this stage to predict the outcome of the arbitration, Teradyne and AutoGuide intend to vigorously defend against the Industrial Automation LLC claims.

Income Taxes

Income Taxes	3 Months Ended
	Apr. 04, 2021
Income Taxes	R. INCOME TAXES A reconciliation of the United States federal statutory corporate tax rate to Teradyne’s effective tax rate was as follows: For the Three Months Ended April 4, March 29, US statutory federal tax rate 21.0 % 21.0 % Foreign taxes (4.7 ) (5.7 ) International provisions of the U.S. Tax Cuts and Jobs Act of 2017 (1.5 ) (0.2 ) Tax credits (1.3 ) (1.9 ) Discrete benefit related to equity compensation (6.2 ) (4.1 ) Other, net 1.0 1.5 Effective tax rate 8.3 % 10.6 % On a quarterly basis, Teradyne evaluates the realizability of the deferred tax assets by jurisdiction and assesses the need for a valuation allowance. As of April 4, 2021, Teradyne believes that it will ultimately realize the deferred tax assets recorded on the condensed consolidated balance sheet. However, should Teradyne believe that it is more-likely-than-not As of April 4, 2021 and December 31, 2020, Teradyne had $16.4 million and $17.9 million, respectively, of reserves for uncertain tax positions. The $1.5 million net decrease in reserves for uncertain tax positions is primarily related to U.S. state research and development credits generated in prior years, as well as U.S. federal research and development credits generated in the current year. As of April 4, 2021, 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 because of a lapse of statutes of limitation. The estimated decrease relates to loss carryforwards, research credits and U.S. manufacturing activities deductions. Teradyne recognizes interest and penalties related to income tax matters in income tax expense. As of April 4, 2021 and December 31, 2020, $1.3 million and $1.2 million, respectively, of interest and penalties were accrued for uncertain tax positions. For the three months ended April 4, 2021 and March 29, 2020, expense of $0.1 million and $0.1 million, respectively, was recorded for interest and penalties related to income tax items. Teradyne qualifies for a tax holiday in Singapore by fulfilling the requirements of an agreement with the Singapore Economic Development Board under which certain headcount and spending requirements must be met. The tax savings due to the tax holiday for the three months ended April 4, 2021 was $6.2 million, or $0.03 per diluted share. The tax savings due to the tax holiday for the three months ended March 29, 2020 was $7.1 million, or $0.04 per diluted share. 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.

Segment Information

Segment Information	3 Months Ended
	Apr. 04, 2021
Segment Reporting [Abstract]
Segment Information	S. SEGMENT INFORMATION Teradyne has four reportable segments (Semiconductor Test, System Test, Industrial Automation and Wireless Test). Each of the reportable segments is also an individual operating segment. The Semiconductor Test segment includes operations related to the design, manufacturing and marketing of semiconductor test products and services. The System Test segment includes operations related to the design, manufacturing and marketing of products and services for defense/aerospace instrumentation test, storage and system level test, and circuit-board test. 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. The Wireless Test segment includes operations related to the design, manufacturing and marketing of wireless test products and services. Each operating segment has a segment manager who is directly accountable to and maintains regular contact with Teradyne’s chief operating decision maker (Teradyne’s chief executive officer) to discuss operating activities, financial results, forecasts, and plans for the segment. Teradyne evaluates performance based on several factors, of which the primary financial measure is business segment income (loss) before income taxes. The accounting policies of the business segments in effect are described in Note B: “Accounting Policies” in Teradyne’s Annual Report on Form 10-K Segment information for the three months ended April 4, 2021 and March 29, 2020 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) Three Months Ended April 4, 2021 Revenues $ 528,063 $ 132,837 $ 79,951 $ 40,898 $ (143 ) $ 781,606 Income (loss) before income taxes (1)(2) 176,368 51,061 (12,967 ) 9,616 (85 ) 223,993 Total assets (3) 1,243,358 179,195 672,596 104,367 1,520,201 3,719,717 Three Months Ended March 29, 2020 Revenues $ 484,489 $ 116,076 $ 60,305 $ 43,485 $ — $ 704,355 Income (loss) before income taxes (1)(2) 153,816 48,407 (15,335 ) 10,220 (39 ) 197,069 Total assets (3) 921,108 137,056 643,011 106,400 1,012,813 2,820,388 (1) Included in Corporate and Other are: contingent consideration adjustments, loss on convertible debt conversions, interest income, interest expense, net foreign exchange gains (losses), pension, intercompany eliminations and acquisition related charges, legal fees and compensation. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, loss on convertible debt conversions 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 Three Months Ended April 4, March 29, (in thousands) Semiconductor Test: Cost of revenues—inventory charge $ 1,079 $ 3,026 Industrial Automation: Cost of revenues—inventory charge $ 1,221 $ — Restructuring and other—acquisition related expenses and compensation — 618 Corporate and Other: Restructuring and other—AutoGuide contingent consideration adjustment $ (7,227 ) $ (7,142 ) Other (income) expense, net—loss on convertible debt conversions 4,069 — Restructuring and other—acquisition related expenses and compensation (513 ) 741 Restructuring and other—MiR contingent consideration adjustment — (2,878 )

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Apr. 04, 2021
Equity [Abstract]
Shareholders' Equity	T. SHAREHOLDERS’ EQUITY Stock Repurchase Program 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. During the three months ended April 4, 2021, Teradyne repurchased 0.4 million shares of common stock for $45.2 million at an average price of $120.73 per share. During the three months ended March 29, 2020, Teradyne repurchased 1.3 million shares of common stock for $79.0 million at an average price of $58.81 per share. The total price includes commissions and is recorded as a reduction to retained earnings. Dividend Holders of Teradyne’s common stock are entitled to receive dividends when they are declared by Teradyne’s Board of Directors. In January 2021, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.10 per share. Dividend payments for the three months ended April 4, 2021 were $16.7 million. In January 2020, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.10 per share. Dividend payments for the three months ended March 29, 2020 were $16.7 million. While Teradyne declared a quarterly cash dividend and authorized a share repurchase program, it may reduce or eliminate the cash dividend or share repurchase program in the future. Future cash dividends and stock repurchases are subject to the discretion of Teradyne’s Board of Directors, which will consider, among other things, Teradyne’s earnings, capital requirements and financial condition.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Apr. 04, 2021
Basis of Presentation	Basis of Presentation The consolidated interim financial statements include the accounts of Teradyne and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. These interim financial statements are unaudited and reflect all normal recurring adjustments that are, in the opinion of management, necessary for the fair statement of such interim financial statements. Certain prior year amounts were reclassified to conform to the current year presentation. The December 31, 2020 condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by United States of America generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in Teradyne’s Annual Report on Form 10-K,
Preparation of Financial Statements and Use of Estimates	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent liabilities. On an on-going COVID-19 10-Q.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Apr. 04, 2021
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 System on-a-Chip Memory System Test Universal Mobile AutoGuide Wireless Test Corporate and Other Total (in thousands) For the Three Months Ended April 4, 2021 (1) Timing of Revenue Recognition Point in Time $ 364,190 $ 101,892 $ 119,314 $ 64,007 $ 14,064 $ (120 ) $ 37,880 $ (143 ) $ 701,084 Over Time 56,040 5,941 13,523 1,594 67 339 3,018 — 80,522 Total $ 420,230 $ 107,833 $ 132,837 $ 65,601 $ 14,131 $ 219 $ 40,898 $ (143 ) $ 781,606 Geographical Market Asia Pacific $ 387,236 $ 104,049 $ 99,520 $ 17,833 $ 3,447 $ — $ 33,532 $ — $ 645,617 Americas 20,779 3,420 27,659 18,153 5,153 219 5,769 (143 ) 81,010 Europe, Middle East and Africa 12,215 364 5,658 29,615 5,531 — 1,597 — 54,980 Total $ 420,230 $ 107,833 $ 132,837 $ 65,601 $ 14,131 $ 219 $ 40,898 $ (143 ) $ 781,606 For the Three Months Ended March 29, 2020 (1) Timing of Revenue Recognition Point in Time $ 348,044 $ 79,398 $ 100,712 $ 47,502 $ 9,097 $ 1,124 $ 41,056 $ — $ 626,933 Over Time 52,095 4,952 15,364 2,195 41 346 2,429 — 77,422 Total $ 400,139 $ 84,350 $ 116,076 $ 49,697 $ 9,138 $ 1,470 $ 43,485 $ — $ 704,355 Geographical Market Asia Pacific $ 362,732 $ 76,110 $ 80,017 $ 10,917 $ 1,593 $ — $ 37,805 $ — $ 569,174 Americas 17,386 6,896 28,291 14,743 3,465 1,470 4,688 — 76,939 Europe, Middle East and Africa 20,021 1,344 7,768 24,037 4,080 — 992 — 58,242 Total $ 400,139 $ 84,350 $ 116,076 $ 49,697 $ 9,138 $ 1,470 $ 43,485 $ — $ 704,355 (1) Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.”

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Apr. 04, 2021
Composition of Inventories, Net	Inventories, net consisted of the following at April 4, 2021 and December 31, 2020: April 4, December 31, 2021 2020 (in thousands) Raw material $ 117,552 $ 114,133 Work-in-process 32,772 25,408 Finished goods 112,150 82,648 $ 262,474 $ 222,189

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Apr. 04, 2021
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of April 4, 2021 and December 31, 2020.​​​​​​​ April 4, 2021 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 $ 417,888 $ — $ 417,888 Cash equivalents 386,694 26,567 — 413,261 Available-for-sale Commercial paper — 306,715 — 306,715 U.S. Treasury securities — 155,190 — 155,190 Corporate debt securities — 83,372 — 83,372 Debt mutual funds 9,288 — — 9,288 U.S. government agency securities — 4,612 — 4,612 Certificates of deposit and time deposits — 966 — 966 Non-U.S. — 619 — 619 Equity securities: Mutual funds 33,151 — — 33,151 $ 847,021 $ 578,041 $ — $ 1,425,062 Derivative assets — 16 — 16 Total $ 847,021 $ 578,057 $ — $ 1,425,078 Liabilities Derivative liabilities $ — $ 393 $ — $ 393 Total $ — $ 393 $ — $ 393 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 804,582 $ 26,567 $ — $ 831,149 Marketable securities — 478,293 — 478,293 Long-term marketable securities 42,439 73,181 — 115,620 Prepayments and other current assets — 16 — 16 Total $ 847,021 $ 578,057 $ — $ 1,425,078 Liabilities Other current liabilities $ — $ 393 $ — $ 393 Total $ — $ 393 $ — $ 393 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 — 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. — 625 — 625 Equity securities: Equity mutual funds 29,420 — — 29,420 $ 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 accrued liabilities $ — $ 504 $ — $ 504 Long-term contingent consideration — — 7,227 7,227 Total $ — $ 504 $ 7,227 $ 7,731
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the three months ended April 4, 2021, and March 29, 2020 were as follows: For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 7,227 $ 39,705 Fair value adjustment (a)(b) (7,227 ) (10,020 ) Foreign currency impact — (361 ) Payments (c) — (8,852 ) Balance at end of period $ — $ 20,472 (a) In the three months ended April 4, 2021, the fair value of contingent consideration for the earn-outs in connection with the acquisition of AutoGuide was reduced to zero, which resulted in a benefit of $7.2 million, primarily due to a decrease in forecasted revenues and earnings before interest and taxes. As of April 4, 2021, the maximum amount of contingent consideration that could be paid in connection with the acquisition of AutoGuide is $100.2 million. The remaining earn-out earn-out non-compliance earn-out non-compliance. (b) In the three months ended March 29, 2020, the fair value of contingent consideration for the earn-outs in connection with the acquisitions of Mobile Industrial Robots Aps (“MiR”) and AutoGuide decreased by $2.9 million and $7.1 million, respectively, due to lower forecasts. (c) In the three months ended March 29, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The carrying amounts and fair values of Teradyne’s financial instruments at April 4, 2021 and December 31, 2020 were as follows: April 4, 2021 December 31, 2020 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 831,149 $ 831,149 $ 914,121 $ 914,121 Marketable securities 593,913 593,913 640,260 640,260 Derivative assets 16 16 95 95 Liabilities Contingent consideration — — 7,227 7,227 Derivative liabilities 393 393 504 504 Convertible debt (1) 367,934 1,664,667 410,111 1,739,553 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note, which includes the equity conversion features.
Schedule of Available-for-Sale Marketable Securities	The following table summarizes the composition of available-for-sale Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Commercial paper $ 306,707 $ 8 $ — $ 306,715 $ 13,996 U.S. Treasury securities 155,337 644 (791 ) 155,190 24,492 Corporate debt securities 79,190 4,340 (158 ) 83,372 25,553 Debt mutual funds 9,242 46 — 9,288 — U.S. government agency securities 4,581 34 (3 ) 4,612 1,413 Certificates of deposit and time deposits 966 — — 966 — Non-U.S. 619 — — 619 — $ 556,642 $ 5,072 $ (952 ) $ 560,762 $ 65,454 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 478,221 $ 95 $ (23 ) $ 478,293 $ 47,468 Long-term marketable securities 78,421 4,977 (929 ) 82,469 17,986 $ 556,642 $ 5,072 $ (952 ) $ 560,762 $ 65,454 The following table summarizes the composition of 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. 625 — — 625 — $ 601,976 $ 9,077 $ (213 ) $ 610,840 $ 70,418 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market 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
Contractual Maturities of Investments Held	The contractual maturities of investments in available-for-sale April 4, 2021 Cost Fair Market Value (in thousands) Due within one year $ 478,221 $ 478,293 Due after 1 year through 5 years 28,597 29,038 Due after 5 years through 10 years 6,103 6,484 Due after 10 years 34,479 37,659 Total $ 547,400 $ 551,474
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	The following table summarizes the fair value of derivative instruments as of April 4, 2021 and December 31, 2020: Balance Sheet Location April 4, December 31, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 16 $ 95 Foreign exchange contracts Other current liabilities (393 ) (504 ) Total derivatives $ (377 ) $ (409 )
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	The following table summarizes the effect of derivative instruments recognized in the statement of operations for the three months ended April 4, 2021 and March 29, 2020: Location of Losses Recognized in Statement of Operations For the Three Months Ended April 4, March 29, (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ 2,118 $ 4,011 (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 three months ended April 4, 2021 and March 29, 2020, net gains from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $0.2 million and $2.0 million, respectively.

Debt (Tables)

Debt (Tables)	3 Months Ended
	Apr. 04, 2021
Components of Convertible Senior Notes	The below tables represent the key components of Teradyne’s convertible senior notes: April 4, 2021 December 31, 2020 (in thousands) Debt principal $ 408,695 $ 459,971 Unamortized discount 40,761 49,860 Net carrying amount of convertible debt $ 367,934 $ 410,111 Reported as follows: April 4, 2021 December 31, 2020 (in thousands) Current debt $ 11,057 $ 33,343 Long-term debt 356,877 376,768 Net carrying amount of convertible debt $ 367,934 $ 410,111 For the Three Months April 4, 2021 March 29, 2020 (in thousands) Contractual interest expense on the coupon $ 1,239 $ 1,438 Amortization of the discount component and debt issue fees recognized as interest expense 3,836 3,792 Total interest expense on the convertible debt $ 5,075 $ 5,230

Prepayments (Tables)

Prepayments (Tables)	3 Months Ended
	Apr. 04, 2021
Prepayments [Abstract]
Schedule of Prepayments and other assets	Prepayments consist of the following and are included in prepayments and other assets on the balance sheet: April 4, December 31, 2021 2020 (in thousands) Contract manufacturer and supplier prepayments $ 291,175 $ 212,286 Prepaid maintenance and other services 15,521 13,116 Prepaid taxes 13,814 9,361 Other prepayments 16,072 15,329 Total prepayments $ 336,582 $ 250,092

Deferred Revenue and Customer_2

Deferred Revenue and Customer Advances (Tables)	3 Months Ended
	Apr. 04, 2021
Revenue Recognition and Deferred Revenue [Abstract]
Deferred Revenue and Customer Advances	Deferred revenue and customer advances consist of the following and are included in short and long-term deferred revenue and customer advances on the balance sheet: April 4, December 31, 2021 2020 (in thousands) Maintenance, service and training $ 78,321 $ 77,654 Customer advances, undelivered elements and other 67,721 63,438 Extended warranty 53,908 51,929 Total deferred revenue and customer advances $ 199,950 $ 193,021

Product Warranty (Tables)

Product Warranty (Tables)	3 Months Ended
	Apr. 04, 2021
Other Accrued Liabilities	Related costs are charged to the warranty accrual as incurred. The balance below is included in other accrued liabilities. For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 16,633 $ 8,996 Accruals for warranties issued during the period 11,881 5,066 Accruals related to pre-existing 447 1,056 Settlements made during the period (5,068 ) (4,147 ) Balance at end of period $ 23,893 $ 10,971
Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances	Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances. For the Three Months Ended April 4, March 29, 2021 2020 (in thousands) Balance at beginning of period $ 51,929 $ 30,677 Deferral of new extended warranty revenue 7,517 7,600 Recognition of extended warranty deferred revenue (5,538 ) (4,774 ) Balance at end of period $ 53,908 $ 33,503

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Apr. 04, 2021
Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions	The fair value was estimated using the Monte Carlo simulation model with the following assumptions: For the Three Months Ended April 4, March 29, 2021 2020 Risk-free interest rate 0.2 % 1.5 % Teradyne volatility-historical 43.9 % 34.9 % NYSE Composite Index volatility-historical 22.9 % 11.4 % Dividend yield 0.4 % 0.6 %
Fair Value of Stock Options Using Assumptions	The fair value of stock options was estimated using the Black-Scholes option-pricing model with the following assumptions: For the Three Months Ended April 4, March 29, 2021 2020 Expected life (years) 5.0 5.0 Risk-free interest rate 0.4 % 1.6 % Volatility-historical 37.8 % 31.6 % Dividend yield 0.4 % 0.6 %

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Apr. 04, 2021
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in accumulated other comprehensive income (loss), which are presented net of tax, consist of the following: Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Service Credit Total (in thousands) Three Months Ended April 4, 2021 Balance at December 31, 2020, net of tax of $0, $1,910, $(1,126), respectively $ 25,389 $ 6,954 $ 1,173 $ 33,516 Other comprehensive loss before reclassifications, net of tax of $0, $(908), $0, respectively (21,123 ) (3,270 ) — (24,393 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(123), $0, respectively — (444 ) (2 ) (446 ) Net current period other comprehensive loss, net of tax of $0, $(1,031), $0, respectively (21,123 ) (3,714 ) (2 ) (24,839 ) Balance at April 4, 2021, net of tax of $0, $879, $(1,126), respectively $ 4,266 $ 3,240 $ 1,171 $ 8,677 Three Months Ended March 29, 2020 Balance at December 31, 2019, net of tax of $0, $946, $(1,124), respectively $ (23,514 ) $ 3,480 $ 1,180 $ (18,854 ) Other comprehensive (loss) income before reclassifications, net of tax of $0, $187, $0, respectively (8,779 ) 1,037 — (7,742 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(145), $0, respectively — (515 ) (2 ) (517 ) Net current period other comprehensive (loss) income, net of tax of $0, $42, $0, respectively (8,779 ) 522 (2 ) (8,259 ) Balance at March 29, 2020, net of tax of $0, $988, $(1,124), respectively $ (32,293 ) $ 4,002 $ 1,178 $ (27,113 )
Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations	Reclassifications out of accumulated other comprehensive income (loss) to the statement of operations for the three months ended April 4, 2021 and March 29, 2020 were as follows: Details about Accumulated Other Comprehensive Income Components For the Three Months Ended Affected Line Item in the Statements of Operations April 4, March 29, 2021 2020 (in thousands) Available-for-sale Unrealized gains, net of tax of $123, $145, respectively $ 444 $ 515 Other (income) Defined benefit postretirement plan: Amortization of prior service credit, net of tax of $0, $0, respectively 2 2 (a) Total reclassifications, net of tax of $123, $145, respectively $ 446 $ 517 Net income (a) The amortization of prior service credit is included in the computation of net periodic postretirement benefit cost. See Note P: “Retirement Plans.”

Goodwill and Acquired Intangi_2

Goodwill and Acquired Intangible Assets (Tables)	3 Months Ended
	Apr. 04, 2021
Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by reportable segments for the three months ended April 4, 2021, were as follows: Industrial Automation System Test Wireless Test Semiconductor Test Total (in thousands) Balance at December 31, 2020 Goodwill $ 433,752 $ 158,699 $ 361,819 $ 262,155 $ 1,216,425 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) 433,752 10,516 7,976 1,615 453,859 Foreign currency translation adjustment (16,156 ) — — (102 ) (16,258 ) Balance at April 4, 2021 Goodwill 417,596 158,699 361,819 262,053 1,200,167 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) $ 417,596 $ 10,516 $ 7,976 $ 1,513 $ 437,601
Schedule of Estimated Intangible Assets Amortization Expense	Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2021 (remainder) 15,896 2022 20,423 2023 19,941 2024 19,634 2025 11,699 Thereafter 5,257
Wireless Test
Schedule of Amortizable Intangible Assets	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet: Gross Carrying Amount Accumulated Amortization Foreign Currency Net Carrying Amount (in thousands) Balance at April 4, 2021 Developed technology $ 272,547 $ (213,459 ) $ (3,198 ) $ 55,890 Customer relationships 57,739 (47,209 ) 150 10,680 Tradenames and trademarks 70,120 (43,716 ) (124 ) 26,280 Total intangible assets $ 400,406 $ (304,384 ) $ (3,172 ) $ 92,850 Balance, December 31, 2020 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

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	3 Months Ended
	Apr. 04, 2021
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: For the Three Months Ended April 4, 2021 March 29, 2020 (in thousands, except per share amounts) Net income for basic and diluted net income per share $ 205,512 $ 176,191 Weighted average common shares-basic 166,491 166,589 Effect of dilutive potential common shares: Incremental shares from assumed conversion of convertible notes (1) 10,310 7,333 Convertible note hedge warrant shares (2) 9,429 5,492 Restricted stock units 1,395 1,163 Stock options 108 134 Employee stock purchase plan 7 25 Dilutive potential common shares 21,249 14,147 Weighted average common shares-diluted 187,740 180,736 Net income per common share-basic $ 1.23 $ 1.06 Net income per common share-diluted $ 1.09 $ 0.97 (1) Incremental shares from assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.55, multiplied by 13.8 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 $39.59, multiplied by 13.8 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period.

Retirement Plans (Tables)

Retirement Plans (Tables)	3 Months Ended
	Apr. 04, 2021
Defined Benefit Pension Plans
Net Periodic Pension and Postretirement Benefit Costs	For the three months ended April 4, 2021 and March 29, 2020, Teradyne’s net periodic pension cost was comprised of the following: For the Three Months Ended April 4, 2021 March 29, 2020 United States Foreign United States Foreign (in thousands) Service cost $ 453 $ 243 $ 433 $ 201 Interest cost 1,100 87 1,522 115 Expected return on plan assets (936 ) (16 ) (1,233 ) (15 ) Total net periodic pension cost $ 617 $ 314 $ 722 $ 301
Postretirement Benefit Plans
Net Periodic Pension and Postretirement Benefit Costs	For the three months ended April 4, 2021 and March 29, 2020, Teradyne’s net periodic postretirement benefit cost was comprised of the following: For the Three Months Ended April 4, March 29, (in thousands) Service cost $ 16 $ 11 Interest cost 44 62 Amortization of prior service credit (2 ) (2 ) Total net periodic postretirement benefit cost $ 58 $ 71

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Apr. 04, 2021
Reconciliation of Effective Tax Rate	A reconciliation of the United States federal statutory corporate tax rate to Teradyne’s effective tax rate was as follows: For the Three Months Ended April 4, March 29, US statutory federal tax rate 21.0 % 21.0 % Foreign taxes (4.7 ) (5.7 ) International provisions of the U.S. Tax Cuts and Jobs Act of 2017 (1.5 ) (0.2 ) Tax credits (1.3 ) (1.9 ) Discrete benefit related to equity compensation (6.2 ) (4.1 ) Other, net 1.0 1.5 Effective tax rate 8.3 % 10.6 %

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Apr. 04, 2021
Segment Information	Segment information for the three months ended April 4, 2021 and March 29, 2020 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate and Other Consolidated (in thousands) Three Months Ended April 4, 2021 Revenues $ 528,063 $ 132,837 $ 79,951 $ 40,898 $ (143 ) $ 781,606 Income (loss) before income taxes (1)(2) 176,368 51,061 (12,967 ) 9,616 (85 ) 223,993 Total assets (3) 1,243,358 179,195 672,596 104,367 1,520,201 3,719,717 Three Months Ended March 29, 2020 Revenues $ 484,489 $ 116,076 $ 60,305 $ 43,485 $ — $ 704,355 Income (loss) before income taxes (1)(2) 153,816 48,407 (15,335 ) 10,220 (39 ) 197,069 Total assets (3) 921,108 137,056 643,011 106,400 1,012,813 2,820,388 (1) Included in Corporate and Other are: contingent consideration adjustments, loss on convertible debt conversions, interest income, interest expense, net foreign exchange gains (losses), pension, intercompany eliminations and acquisition related charges, legal fees and compensation. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, loss on convertible debt conversions 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 Three Months Ended April 4, March 29, (in thousands) Semiconductor Test: Cost of revenues—inventory charge $ 1,079 $ 3,026 Industrial Automation: Cost of revenues—inventory charge $ 1,221 $ — Restructuring and other—acquisition related expenses and compensation — 618 Corporate and Other: Restructuring and other—AutoGuide contingent consideration adjustment $ (7,227 ) $ (7,142 ) Other (income) expense, net—loss on convertible debt conversions 4,069 — Restructuring and other—acquisition related expenses and compensation (513 ) 741 Restructuring and other—MiR contingent consideration adjustment — (2,878 )

Revenue - Additional Informatio

Revenue - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Deferred Revenue And Customer Advances	$ 27.8	$ 39.5
Trade Accounts Receivable	$ 7.3	$ 46.8
Short-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	95.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	12 months
Revenue, Remaining Performance Obligation, Amount	$ 1,456
Long-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	4.00%
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		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Disaggregation of Revenue [Line Items]
Total	[1]	$ 781,606	$ 704,355
Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		528,063	484,489
System Test
Disaggregation of Revenue [Line Items]
Total	[1]	132,837	116,076
Industrial Automation
Disaggregation of Revenue [Line Items]
Total		79,951	60,305
Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	40,898	43,485
Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(143)
Point in Time
Disaggregation of Revenue [Line Items]
Total	[1]	701,084	626,933
Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	119,314	100,712
Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	37,880	41,056
Point in Time | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(143)
Over Time
Disaggregation of Revenue [Line Items]
Total	[1]	80,522	77,422
Over Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	13,523	15,364
Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	3,018	2,429
Americas
Disaggregation of Revenue [Line Items]
Total	[1]	81,010	76,939
Americas | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	27,659	28,291
Americas | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	5,769	4,688
Americas | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(143)
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total	[1]	54,980	58,242
Europe, Middle East and Africa | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	5,658	7,768
Europe, Middle East and Africa | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,597	992
Asia Pacific
Disaggregation of Revenue [Line Items]
Total	[1]	645,617	569,174
Asia Pacific | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	99,520	80,017
Asia Pacific | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	33,532	37,805
SOC | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	420,230	400,139
SOC | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	364,190	348,044
SOC | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	56,040	52,095
SOC | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	20,779	17,386
SOC | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	12,215	20,021
SOC | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	387,236	362,732
Memory | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	107,833	84,350
Memory | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	101,892	79,398
Memory | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	5,941	4,952
Memory | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	3,420	6,896
Memory | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	364	1,344
Memory | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	104,049	76,110
Universal Robots (UR) | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	65,601	49,697
Universal Robots (UR) | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	64,007	47,502
Universal Robots (UR) | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,594	2,195
Universal Robots (UR) | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	18,153	14,743
Universal Robots (UR) | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	29,615	24,037
Universal Robots (UR) | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	17,833	10,917
MiR | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	14,131	9,138
MiR | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	14,064	9,097
MiR | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	67	41
MiR | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	5,153	3,465
MiR | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	5,531	4,080
MiR | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	3,447	1,593
Autoguide LLC [Member] | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	219	1,470
Autoguide LLC [Member] | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	(120)	1,124
Autoguide LLC [Member] | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	339	346
Autoguide LLC [Member] | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	$ 219	$ 1,470
[1]	Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.”

Disaggregated Revenue by Prim_2

Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Accounting Policies [Abstract]
Revenue on leases	$ 3.1	$ 1.8

Composition of Inventories, Net

Composition of Inventories, Net (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Raw material	$ 117,552	$ 114,133
Work-in-process	32,772	25,408
Finished goods	112,150	82,648
Inventories, net	$ 262,474	$ 222,189

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Apr. 04, 2021	Dec. 31, 2020
Inventory [Line Items]
Inventory reserves	$ 107.8	$ 110.6

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Apr. 04, 2021	Mar. 29, 2020	Dec. 31, 2020
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized gain	$ 1,200,000	$ 1,400,000
Available-for-sale securities, realized loss		100,000
Fair market value of investments with unrealized losses less than one year	65,500,000		$ 70,400,000
Unrealized Gain (loss) on contracts	200,000	2,000,000
Equity securities unrealized gain	1,400,000
Equity securities unrealized loss		$ 6,000,000
Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available for sale securities with out contractual maturity date	9,300
Foreign Exchange Contracts
Financial Instruments and Fair Value [Line Items]
Unrealized Gain (loss) on contracts	$ 156,800,000		$ 152,900,000

Schedule of Fair Value of Finan

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	$ 560,762	$ 610,840
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	155,190	258,304
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	306,715	254,413
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,372	83,615
Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	966	979
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,612	4,339
Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	9,288	8,565
Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	619	625
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,425,062	1,554,381
Derivative assets	16	95
Total	1,425,078	1,554,476
Contingent consideration		7,227
Derivative liabilities	393	504
Total	393	7,731
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	417,888	443,166
Fair Value, Measurements, Recurring | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	413,261	470,955
Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	155,190	258,304
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	306,715	254,413
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	83,372	83,615
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	966	979
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	4,612	4,339
Fair Value, Measurements, Recurring | Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	9,288	8,565
Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	619	625
Fair Value, Measurements, Recurring | Equity Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale equity securities	33,151	29,420
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	847,021	828,919
Total	847,021	828,919
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	417,888	443,166
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	386,694	347,768
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	0
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	9,288	8,565
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	33,151	29,420
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	578,041	725,462
Derivative assets	16	95
Total	578,057	725,557
Derivative liabilities	393	504
Total	393	504
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	26,567	123,187
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	155,190	258,304
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	306,715	254,413
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	83,372	83,615
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	966	979
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	4,612	4,339
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	$ 619	625
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration		7,227
Total		$ 7,227

Schedule of Reported Financial

Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,425,078	$ 1,554,476
Liabilities	393	7,731
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	393	504
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	831,149	914,121
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	478,293	522,280
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	115,620	117,980
Prepayments and other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	16	95
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		7,227
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	847,021	828,919
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	804,582	790,934
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	42,439	37,985
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	578,057	725,557
Liabilities	393	504
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	393	504
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	26,567	123,187
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	478,293	522,280
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	73,181	79,995
Significant Other Observable Inputs (Level 2) | Prepayments and other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 16	95
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		7,227
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities		$ 7,227

Schedule of Changes in Fair Val

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		$ 7,227	$ 39,705
Fair value adjustment	[1],[2]	$ (7,227)	(10,020)
Foreign currency impact			(361)
Payments	[3]		(8,852)
Balance at end of period			$ 20,472
[1]	In the three months ended April 4, 2021, the fair value of contingent consideration for the earn-outs in connection with the acquisition of AutoGuide was reduced to zero, which resulted in a benefit of $7.2 million, primarily due to a decrease in forecasted revenues and earnings before interest and taxes. As of April 4, 2021, the maximum amount of contingent consideration that could be paid in connection with the acquisition of AutoGuide is $100.2 million. The remaining earn-out periods end on December 31, 2021 and December 31, 2022. The sellers of AutoGuide have filed an arbitration claim against Teradyne related to the earn-out alleging non-compliance with the earn-out provisions of the AutoGuide acquisition agreement. Teradyne disputes the allegations 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.
[2]	In the three months ended March 29, 2020, the fair value of contingent consideration for the earn-outs in connection with the acquisitions of Mobile Industrial Robots Aps (“MiR”) and AutoGuide decreased by $2.9 million and $7.1 million, respectively, due to lower forecasts.
[3]	In the three months ended March 29, 2020, Teradyne paid $8.9 million of contingent consideration for the earn-out in connection with the acquisition of MiR.

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
		Apr. 04, 2021	Mar. 29, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration			$ 8,852
Increase (decrease) in contingent consideration		$ (7,227)	(10,020)
Fair value of contingent consideration, Acquisition, Earnings.	[1],[2]	(7,227)	(10,020)
Maximum amount of contingent consideration paid for acquisition			8,852
Universal Robots (UR)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration			8,900
Maximum amount of contingent consideration paid for acquisition			8,900
MiR
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Increase (decrease) in contingent consideration			2,900
Autoguide LLC [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration		100,200
Increase (decrease) in contingent consideration			$ 7,100
Fair value of contingent consideration, Acquisition, Earnings.		7,200
Maximum amount of contingent consideration paid for acquisition		$ 100,200
[1]	In the three months ended April 4, 2021, the fair value of contingent consideration for the earn-outs in connection with the acquisition of AutoGuide was reduced to zero, which resulted in a benefit of $7.2 million, primarily due to a decrease in forecasted revenues and earnings before interest and taxes. As of April 4, 2021, the maximum amount of contingent consideration that could be paid in connection with the acquisition of AutoGuide is $100.2 million. The remaining earn-out periods end on December 31, 2021 and December 31, 2022. The sellers of AutoGuide have filed an arbitration claim against Teradyne related to the earn-out alleging non-compliance with the earn-out provisions of the AutoGuide acquisition agreement. Teradyne disputes the allegations 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.
[2]	In the three months ended March 29, 2020, the fair value of contingent consideration for the earn-outs in connection with the acquisitions of Mobile Industrial Robots Aps (“MiR”) and AutoGuide decreased by $2.9 million and $7.1 million, respectively, due to lower forecasts.

Schedule of Carrying Amounts an

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands		Apr. 04, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Marketable securities		$ 560,762	$ 610,840
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		831,149	914,121
Marketable securities		593,913	640,260
Derivative assets		16	95
Contingent consideration			7,227
Derivative liabilities		393	504
Convertible debt	[1]	367,934	410,111
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		831,149	914,121
Marketable securities		593,913	640,260
Derivative assets		16	95
Contingent consideration			7,227
Derivative liabilities		393	504
Convertible debt	[1]	$ 1,664,667	$ 1,739,553
[1]	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note, which includes the equity conversion features.

Schedule of Available for Sale

Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 556,642	$ 601,976
Available-for-sale marketable securities, Unrealized Gain	5,072	9,077
Available-for-sale marketable securities, Unrealized (Loss)	(952)	(213)
Available-for-sale marketable securities, Fair Market Value	560,762	610,840
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	65,454	70,418
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	155,337	257,132
Available-for-sale marketable securities, Unrealized Gain	644	1,330
Available-for-sale marketable securities, Unrealized (Loss)	(791)	(158)
Available-for-sale marketable securities, Fair Market Value	155,190	258,304
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	24,492	17,243
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	306,707	254,404
Available-for-sale marketable securities, Unrealized Gain	8	10
Available-for-sale marketable securities, Unrealized (Loss)		(1)
Available-for-sale marketable securities, Fair Market Value	306,715	254,413
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	13,996	12,173
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	79,190	76,129
Available-for-sale marketable securities, Unrealized Gain	4,340	7,539
Available-for-sale marketable securities, Unrealized (Loss)	(158)	(53)
Available-for-sale marketable securities, Fair Market Value	83,372	83,615
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	25,553	39,896
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	966	979
Available-for-sale marketable securities, Fair Market Value	966	979
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	4,581	4,294
Available-for-sale marketable securities, Unrealized Gain	34	46
Available-for-sale marketable securities, Unrealized (Loss)	(3)	(1)
Available-for-sale marketable securities, Fair Market Value	4,612	4,339
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,413	1,106
Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	9,242	8,413
Available-for-sale marketable securities, Unrealized Gain	46	152
Available-for-sale marketable securities, Fair Market Value	9,288	8,565
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	619	625
Available-for-sale marketable securities, Fair Market Value	$ 619	$ 625

Schedule of Reported Available

Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 556,642	$ 601,976
Available-for-sale marketable securities, Unrealized Gain	5,072	9,077
Available-for-sale marketable securities, Unrealized (Loss)	(952)	(213)
Available-for-sale marketable securities, Fair Market Value	560,762	610,840
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	65,454	70,418
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	478,221	522,228
Available-for-sale marketable securities, Unrealized Gain	95	92
Available-for-sale marketable securities, Unrealized (Loss)	(23)	(40)
Available-for-sale marketable securities, Fair Market Value	478,293	522,280
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	47,468	61,806
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	78,421	79,748
Available-for-sale marketable securities, Unrealized Gain	4,977	8,985
Available-for-sale marketable securities, Unrealized (Loss)	(929)	(173)
Available-for-sale marketable securities, Fair Market Value	82,469	88,560
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 17,986	$ 8,612

Contractual Maturities of Inves

Contractual Maturities of Investments in Debt Securities Held (Detail) $ in Thousands	Apr. 04, 2021USD ($)
Schedule of Available-for-sale Securities
Due within one year, cost	$ 478,221
Due after 1 year through 5 years, cost	28,597
Due after 5 years through 10 years, cost	6,103
Due after 10 years, cost	34,479
Total, cost	547,400
Due within one year, fair market value	478,293
Due after 1 year through 5 years, fair market value	29,038
Due after 5 years through 10 years, fair market value	6,484
Due after 10 years, fair maket value	37,659
Total, fair market value	$ 551,474

Schedule of Derivative Instrume

Schedule of Derivative Instruments in Statement of Financial Position at Fair Value (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net	$ (377)	$ (409)
Not Designated as Hedging Instrument | Foreign currency forward contracts | Prepayments
Derivatives, Fair Value [Line Items]
Derivative assets	16	95
Not Designated as Hedging Instrument | Foreign currency forward contracts | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (393)	$ (504)

Schedule of Effect of Derivativ

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Losses on derivatives recognized in statements of operations	$ 2,118	$ 4,011

Schedule of Effect of Derivat_2

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on foreign currency transactions	$ 0.2	$ 2

Debt - Additional Information (

Debt - Additional Information (Detail)	May 07, 2021USD ($)	May 01, 2020USD ($)	Dec. 12, 2016USD ($)Customer$ / sharesshares	Jun. 30, 2021USD ($)	Apr. 04, 2021USD ($)$ / sharesshares	Mar. 29, 2020USD ($)shares	Dec. 31, 2020USD ($)
Debt Instrument
Repurchase of common stock					$ 45,188,000	$ 79,039,000
Repurchase of stock, shares | shares					400,000	1,300,000
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 rates applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.50% 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					$ 1,233,000		$ 3,787,000
Convertible Common Shares [Member]
Debt Instrument
Convertible common shares					51,300,000
Shares Issued, Stock Options Exercised					1,200,000
Increase in debt principal, Additional conversion				$ 15,600,000
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		408,695,000		459,971,000
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, date of first required payment			Jun. 15, 2017
Debt instrument, conversion option expiration date			Sep. 15, 2023
Debt instrument conversion price | $ / shares			$ 31.55		$ 31.55
Shares that would be issued upon conversion | shares			13		13,000,000
Strike price per share of warrant | $ / shares					$ 39.59
Debt instrument, convertible, carrying amount of equity component					$ 100,800,000	$ 100,800,000
Debt instrument, effective annual interest rate					5.00%
Financing cost					$ 2,700,000	$ 7,200,000
Debt issuance costs, amortization period						7 years
Unamortized discount							$ 40,800,000
Debt Instrument, convertible, remaining discount amortization period							2 years 8 months 12 days
Value of notes converted					1,668,600,000
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Subsequent Event [Member]
Debt Instrument
Debt instrument conversion converted instrument amount	$ 66,900,000
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
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
Revolving credit facility costs incurred					$ 3,500,000

Components of Convertible Senio

Components of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020	Dec. 12, 2016
Debt Instrument
Current debt	$ 11,057	$ 33,343
Long-term debt	356,877	376,768
Net carrying amount of convertible debt	367,934	410,111
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Debt principal	408,695	459,971	$ 460,000
Unamortized discount	40,761	49,860
Net carrying amount of convertible debt	$ 367,934	$ 410,111

Interest Expense on Convertible

Interest Expense on Convertible Senior Notes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Debt Instrument
Contractual interest expense on the coupon	$ 1,239	$ 1,438
Amortization of the discount component and debt issue fees recognized as interest expense	3,836	3,792
Total interest expense on the convertible debt	$ 5,075	$ 5,230

Prepayments (Detail)

Prepayments (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020
Prepaid And Other Current Assets [Line Items]
Contract manufacturer and supplier prepayments	$ 291,175	$ 212,286
Prepaid maintenance and other services	15,521	13,116
Prepaid taxes	13,814	9,361
Other prepayments	16,072	15,329
Total prepayments	$ 336,582	$ 250,092

Deferred Revenue and Customer_3

Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	Apr. 04, 2021	Dec. 31, 2020	Mar. 29, 2020	Dec. 31, 2019
Deferred Revenue Arrangement
Maintenance, service and training	$ 78,321	$ 77,654
Customer advances, undelivered elements and other	67,721	63,438
Extended warranty	53,908	51,929	$ 33,503	$ 30,677
Total deferred revenue and customer advances	$ 199,950	$ 193,021

Product Warranty (Detail)

Product Warranty (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 16,633	$ 8,996
Accruals for warranties issued during the period	11,881	5,066
Accruals related to pre-existing warranties	447	1,056
Settlements made during the period	(5,068)	(4,147)
Balance at end of period	$ 23,893	$ 10,971

Extended Product Warranty of Sh

Extended Product Warranty of Short and Long-Term Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 51,929	$ 30,677
Deferral of new extended warranty revenue	7,517	7,600
Recognition of extended warranty deferred revenue	(5,538)	(4,774)
Balance at end of period	$ 53,908	$ 33,503

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - $ / shares shares in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020	Sep. 27, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Stock price		$ 72.10	$ 113.48
Stock Options | Measurement Input, Expected Dividend Payment [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Estimated annual dividend amount per share	$ 0.40	$ 0.40
Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments	4 years
Percentage of awards vesting on the first anniversary of grant date	100.00%
Restricted Stock Units | Director
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments	1 year
TSR Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period	3 years	3 years
Minimum age of retirement to be eligible for PRSUs	60 years
Minimum years of service for retirement to be eligible for PRSUs	10 years
Restricted stock unit awards granted	0.1
Weighted average grant date fair value of restricted stock units granted	$ 125.02	$ 89.93
Stock price	0.40	72.10
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	113.48
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	0.00%
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	200.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of common stock price paid	100.00%
PBIT Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted	0.1
Weighted average grant date fair value of restricted stock units granted	$ 112.28	$ 70.94
Service-Based Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted	0.3	0.4
Weighted average grant date fair value of restricted stock units granted	$ 112.55	$ 70.98
Service-Based Restricted Stock Units | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted	0.1
Weighted average grant date fair value of restricted stock units granted	$ 36.60	$ 20.67

Schedule of Estimated Fair Valu

Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail)	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility	37.80%	31.60%
New York Stock Exchange Composite Index
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility	22.90%	11.40%
TSR Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rate	0.20%	1.50%
Expected historical volatility	43.90%	34.90%
Dividend yield	0.40%	0.60%

Schedule of Estimated Fair Va_2

Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail)	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Share-based Compensation Arrangement by Share-based Payment Award
Volatility-historical	37.80%	31.60%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Expected life (years)	5 years	5 years
Risk-free interest rate	0.40%	1.60%
Dividend yield	0.40%	0.60%

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		$ 2,207,018	$ 1,480,158
Other comprehensive loss		(24,839)	(8,259)
Balance		2,324,553	1,550,673
Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		25,389	(23,514)
Other comprehensive (loss) income before reclassifications, net of tax		(21,123)	(8,779)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		0	0
Other comprehensive loss		(21,123)	(8,779)
Balance		4,266	(32,293)
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		6,954	3,480
Other comprehensive (loss) income before reclassifications, net of tax		(3,270)	1,037
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		(444)	(515)
Other comprehensive loss		(3,714)	522
Balance		3,240	4,002
Retirement Plans Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		1,173	1,180
Other comprehensive (loss) income before reclassifications, net of tax		0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	[1]	(2)	(2)
Other comprehensive loss		(2)	(2)
Balance		1,171	1,178
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		33,516	(18,854)
Other comprehensive (loss) income before reclassifications, net of tax		(24,393)	(7,742)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		(446)	(517)
Other comprehensive loss		(24,839)	(8,259)
Balance		$ 8,677	$ (27,113)
[1]	The amortization of prior service credit is included in the computation of net periodic postretirement benefit cost. See Note P: “Retirement Plans.”

Changes in Accumulated Other _2

Changes in Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss), tax	$ (123)	$ (145)
Foreign currency translation adjustments, tax	0	0	$ 0	$ 0
Unrealized (losses) gains on marketable securities, tax	879	988	1,910	946
Retirement plans prior service benefit, tax	(1,126)	(1,124)	$ (1,126)	$ (1,124)
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	(908)	187
Amounts reclassified from accumulated other comprehensive income (loss), tax	(123)	(145)
Other comprehensive income (loss), tax	(1,031)	42
Retirement Plans 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	0	0
Other comprehensive income (loss), tax	$ 0	$ 0

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income (expense)		$ 444	$ 515
Retirement Plans Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax	[1]	2	2
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, net of tax		$ 446	$ 517
[1]	The amortization of prior service credit is included in the computation of net periodic postretirement benefit cost. See Note P: “Retirement Plans.”

Reclassifications Out of Accu_2

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 123	$ 145
Unrealized (Losses) Gains on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	123	145
Amortization of Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 0	$ 0

Goodwill and Acquired Intangi_3

Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Goodwill and Intangible Assets Disclosure [Line Items]
Acquired intangible assets amortization	$ 5,536	$ 9,891

Changes in Carrying Amount of G

Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 1,200,167	$ 1,216,425
Accumulated impairment losses	(762,566)	(762,566)
Foreign currency translation adjustment	(16,258)
Goodwill	437,601	453,859
Industrial Automation
Goodwill [Line Items]
Goodwill	417,596	433,752
Accumulated impairment losses	0	0
Foreign currency translation adjustment	(16,156)
Goodwill	417,596	433,752
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Foreign currency translation adjustment	0
Goodwill	10,516	10,516
Wireless Test
Goodwill [Line Items]
Goodwill	361,819	361,819
Accumulated impairment losses	(353,843)	(353,843)
Foreign currency translation adjustment	0
Goodwill	7,976	7,976
Semiconductor Test
Goodwill [Line Items]
Goodwill	262,053	262,155
Accumulated impairment losses	(260,540)	(260,540)
Foreign currency translation adjustment	(102)
Goodwill	$ 1,513	$ 1,615

Schedule of Amortizable Intangi

Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 04, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 400,406	$ 408,906
Accumulated Amortization	(304,384)	(307,347)
Foreign Currency Translation Adjustment	(3,172)	(620)
Net Carrying Amount	92,850	100,939
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	272,547	272,547
Accumulated Amortization	(213,459)	(210,479)
Foreign Currency Translation Adjustment	(3,198)	(1,610)
Net Carrying Amount	55,890	60,458
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	57,739	66,239
Accumulated Amortization	(47,209)	(54,524)
Foreign Currency Translation Adjustment	150	305
Net Carrying Amount	10,680	12,020
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	70,120	70,120
Accumulated Amortization	(43,716)	(42,344)
Foreign Currency Translation Adjustment	(124)	685
Net Carrying Amount	$ 26,280	$ 28,461

Schedule of Estimated Intangibl

Schedule of Estimated Intangible Asset Amortization Expense (Detail) $ in Thousands	Apr. 04, 2021USD ($)
Finite-Lived Intangible Assets
2021 (remainder)	$ 15,896
2022	20,423
2023	19,941
2024	19,634
2025	11,699
Thereafter	$ 5,257

Computation of Basic and Dilute

Computation of Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Apr. 04, 2021	Mar. 29, 2020
Net Income Loss Per Common Share
Net income for basic and diluted net income per share		$ 205,512	$ 176,191
Weighted average common shares-basic		166,491	166,589
Incremental shares from assumed conversion of convertible notes	[1]	10,310	7,333
Convertible note hedge warrant shares	[2]	9,429	5,492
Employee stock purchase plan		7	25
Dilutive potential common shares		21,249	14,147
Weighted average common shares-diluted		187,740	180,736
Net income per common share-basic		$ 1.23	$ 1.06
Net income per common share-diluted		$ 1.09	$ 0.97
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		1,395	1,163
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements		108	134
[1]	Incremental shares from assumed conversion of the convertible notes were calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.55, multiplied by 13.8 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 $39.59, multiplied by 13.8 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period.

Computation of Basic and Dilu_2

Computation of Basic and Diluted Net Income Per Common Share (Parenthetical) (Detail) shares in Millions	3 Months Ended
	Apr. 04, 2021$ / sharesshares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 31.55
Shares that would be issued upon conversion | shares	13.8
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 39.59
Shares that would be issued upon conversion | shares	13.8

Net Income Per Common Share - A

Net Income Per Common Share - Additional Information (Detail) shares in Millions	3 Months Ended
	Mar. 29, 2020shares
Net Income Loss Per Common Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.3

Restructuring and Other - Addit

Restructuring and Other - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Restructuring Cost and Reserve
Contingent consideration adjustment	$ (7,227)	$ (10,020)
Semiconductor Test
Restructuring Cost and Reserve
Contingent consideration adjustment	10,000
Severance benefit and charges	200	1,400
Acquisition related costs	200
Contract termination settlement fee		$ 700
TER Corporate And Eliminations | Universal Robots (UR)
Restructuring Cost and Reserve
Contingent consideration adjustment	$ 7,200

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - United States Plans - Annuity Plan For Participants In The US Qualified Pension Plan [Member] $ in Millions	3 Months Ended
	Apr. 04, 2021USD ($)
Defined Benefit Plan Disclosure
Pension benefit obligation acturial gain loss	$ 0.8
Defined benefit obligation increase decrease for remeasurement due to settlement	$ 0.3

Schedule of Net Periodic Pensio

Schedule of Net Periodic Pension and Postretirement (income) Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
UNITED STATES
Defined Benefit Plan Disclosure
Service cost	$ 453	$ 433
Interest cost	1,100	1,522
Expected return on plan assets	(936)	(1,233)
Total net periodic pension cost	617	722
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	243	201
Interest cost	87	115
Expected return on plan assets	(16)	(15)
Total net periodic pension cost	314	301
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Service cost	16	11
Interest cost	44	62
Amortization of prior service cost	(2)	(2)
Total net periodic pension cost	$ 58	$ 71

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Oct. 18, 2019	Apr. 04, 2021
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments		$ 680,700,000
Purchase commitments less than one year		$ 666,800,000
Legal claims, damage sought by party	$ 106,875,000

Schedule of Reconciliation of E

Schedule of Reconciliation of Effective Tax Rate (Detail)	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Income Tax Disclosure [Line Items]
US statutory federal tax rate	21.00%	21.00%
Foreign taxes	(4.70%)	(5.70%)
International provisions of the U.S. Tax Cuts and Jobs Act of 2017	(1.50%)	(0.20%)
Tax credits	(1.30%)	(1.90%)
Discrete benefit related to equity compensation	(6.20%)	(4.10%)
Other, net	1.00%	1.50%
Effective tax rate	8.30%	10.60%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020	Dec. 31, 2020
Income Taxes [Line Items]
Tax savings due to the tax holiday	$ 6.2	$ 7.1
Tax savings due to the tax holiday, per share	$ 0.03	$ 0.04
Accrued interest and penalties	$ 1.3		$ 1.2
Interest and penalties related to income tax, expense (benefit)	0.1	$ 0.1
Uncertain tax positions	16.4		$ 17.9
Net decrease in reserves for uncertain tax positions	(1.5)
Possible Lapse Of Statutes Of Limitations [Member]
Income Taxes [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 1.6

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended
	Apr. 04, 2021Segments
Segment Reporting Information [Line Items]
Number of Operating Segments	4

Schedule of Segment Information

Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended
		Apr. 04, 2021		Mar. 29, 2020		Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	[1]	$ 781,606		$ 704,355
Income (loss) before income taxes	[2],[3]	223,993		197,069
Total assets		3,719,717	[4]	2,820,388	[4]	$ 3,652,346
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		528,063		484,489
Income (loss) before income taxes	[2],[3]	176,368		153,816
Total assets	[4]	1,243,358		921,108
System Test
Segment Reporting Information [Line Items]
Revenues	[1]	132,837		116,076
Income (loss) before income taxes	[2],[3]	51,061		48,407
Total assets	[4]	672,596		643,011
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		79,951		60,305
Income (loss) before income taxes	[2],[3]	(12,967)		(15,335)
Total assets	[4]	179,195		137,056
Wireless Test
Segment Reporting Information [Line Items]
Revenues	[1]	40,898		43,485
Income (loss) before income taxes	[2],[3]	9,616		10,220
Total assets	[4]	104,367		106,400
Corporate And Others [Member]
Segment Reporting Information [Line Items]
Revenues		(143)
Income (loss) before income taxes	[2],[3]	(85)		(39)
Total assets	[4]	$ 1,520,201		$ 1,012,813
[1]	Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.”
[2]	Included in Corporate and Other are: contingent consideration adjustments, loss on convertible debt conversions, interest income, interest expense, net foreign exchange gains (losses), pension, intercompany eliminations and acquisition related charges, legal fees and compensation.
[3]	Included in income (loss) before taxes are charges and credits related to restructuring and other, loss on convertible debt conversions and inventory charges.
[4]	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 I

Schedule of Segment Reporting Information by Segment Charges (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Segment Reporting Information [Line Items]
Contingent consideration adjustment	$ (7,227)	$ (10,020)
Other (income) expense, net—loss on convertible debt conversions	(3,824)	(6,849)
Semiconductor Test
Segment Reporting Information [Line Items]
Acquisition related costs	200
Cost of revenues—inventory charge	1,079	3,026
Contingent consideration adjustment	10,000
Industrial Automation
Segment Reporting Information [Line Items]
Acquisition related costs		618
Cost of revenues—inventory charge	1,221
Corporate And Eliminations | Restructuring and other
Segment Reporting Information [Line Items]
Acquisition related costs	(513)	741
Other (income) expense, net—loss on convertible debt conversions	4,069
Corporate And Eliminations | Universal Robots (UR) | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment	$ (7,227)	(7,142)
Corporate And Eliminations | Mobile Industrial Robots (MiR) | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment		$ (2,878)

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020	Jan. 31, 2021	Jan. 01, 2021	Jan. 31, 2020
Cumulative repurchases, shares	0.4	1.3
Common stock average price	$ 120.73	$ 58.81
Dividends Payable, Amount Per Share			$ 0.10		$ 0.10
Dividend payment	$ 16,667	$ 16,686
Treasury Stock, Value				$ 600,000
Treasury Stock, Shares				2,000
Share Repurchase Program [Member]
Cumulative repurchases, value	$ 45,200	$ 79,000