Teradyne (TER) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document Information
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	TER
Entity Registrant Name	TERADYNE, INC
Entity Central Index Key	97,210
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		195,422,673
Entity Public Float			$ 5,900,000,000

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents		$ 429,843	$ 307,884
Marketable securities		1,347,979	871,024
Accounts receivable, less allowance for doubtful accounts of $2,219 and $2,356 in 2017 and 2016, respectively		272,783	192,444
Inventories, net		107,525	135,958
Prepayments and other current assets		112,151	116,493
Total current assets		2,270,281	1,623,803
Property, plant and equipment, net		268,447	253,821
Marketable securities		125,926	433,843
Deferred tax assets		84,026	107,405
Retirement plans assets		17,491	7,712
Other assets		12,275	12,165
Acquired intangible assets, net		79,088	100,401
Goodwill		252,011	223,343
Total assets	[1]	3,109,545	2,762,493
Current liabilities:
Accounts payable		86,393	95,362
Accrued employees' compensation and withholdings		141,694	109,944
Deferred revenue and customer advances		83,614	84,478
Other accrued liabilities		59,083	51,382
Contingent consideration		24,497	1,050
Income taxes payable		59,055	30,480
Total current liabilities		454,336	372,696
Retirement plans liabilities		119,776	106,938
Long-term deferred revenue and customer advances		30,127	23,463
Long-term contingent consideration		20,605	37,282
Deferred tax liabilities		6,720	12,144
Long-term other accrued liabilities		10,273	28,642
Long-term income taxes payable		148,075
Long-term debt		365,987	352,669
Total liabilities		1,155,899	933,834
Commitments and contingencies (Note K)
SHAREHOLDERS' EQUITY
Common stock, $0.125 par value, 1,000,000 shares authorized, 195,548 and 199,177 shares issued and outstanding at December 31, 2017 and 2016, respectively		24,444	24,897
Additional paid-in capital		1,638,413	1,593,684
Accumulated other comprehensive income (loss)		18,776	(20,214)
Retained earnings		272,013	230,292
Total shareholders' equity		1,953,646	1,828,659
Total liabilities and shareholders' equity		$ 3,109,545	$ 2,762,493
[1]	Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts receivable, less allowance for doubtful accounts	$ 2,219	$ 2,356
Common stock, par value	$ 0.125	$ 0.125
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	195,548,000	199,177,000
Common stock, shares outstanding	195,548,000	199,177,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1],[2]	Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016		Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Revenues:
Products	$ 388,282		$ 412,854		$ 610,356		$ 373,204		$ 303,667	[6],[7]	$ 334,610		$ 456,832		$ 358,139		$ 1,784,695		$ 1,453,248		$ 1,340,566
Services	91,133		90,524		86,545		83,709		76,322	[6],[7]	75,865		74,960		72,855		351,911		300,002		299,012
Total revenues	479,415		503,378		696,901		456,913		379,989	[6],[7]	410,475		531,792		430,994		2,136,606	[11]	1,753,250	[11]	1,639,578	[11]
Cost of revenues:
Cost of products	166,667		169,744		267,171		154,966		127,481	[6],[7]	148,266		215,795		167,555		758,548		659,097		591,772
Cost of services	39,813		38,848		38,511		37,014		33,502	[6],[7]	34,850		33,127		33,107		154,186		134,586		132,163
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	206,480		208,592		305,682		191,980		160,983	[6],[7]	183,116		248,922		200,662		912,734		793,683		723,935
Gross profit	272,935		294,786		391,219		264,933		219,006	[6],[7]	227,359		282,870		230,332		1,223,872		959,567		915,643
Operating expenses:
Selling and administrative	88,006		86,244		89,131		84,906		76,289	[6],[7]	78,794		81,425		79,174		348,287		315,682		306,313
Engineering and development	70,564		77,190		81,728		76,182		70,052	[6],[7]	71,400		76,109		73,464		305,665		291,025		292,250
Acquired intangible assets amortization	7,384		7,028		8,166		7,952		7,923	[6],[7]	8,487		16,244		19,994		30,530		52,648		69,031
Restructuring and other	8,970		(4,407)		2,288		2,511		5,570	[6],[7]	12,177		2,608		1,587		9,362		21,942		5,080
Goodwill impairment									0				254,946				0		254,946
Acquired intangible assets impairment													83,339						83,339
Total operating expenses	174,924		166,055		181,313		171,551		159,834	[6],[7]	170,858		514,671		174,219		693,844		1,019,582		672,674
Income (loss) from operations	98,011		128,731		209,906		93,382		59,172	[6],[7]	56,501		(231,801)		56,113		530,028		(60,015)		242,969
Non-operating (income) expenses:
Interest income	(6,476)		(4,517)		(3,292)		(3,520)		(3,095)	[6],[7]	(2,892)		(1,666)		(1,642)		(17,805)		(9,296)		(7,214)
Interest expense	5,380		5,372		5,509		5,402		1,604	[6],[7]	633		691		710		21,663		3,637		1,876
Other (income) expense, net	1,023		439		812		(516)		1,779	[6],[7]	(921)		(9)		(147)		1,758		704		(4,817)
Income (loss) before income taxes	98,084		127,437		206,877		92,016		58,884	[6],[7]	59,681		(230,817)		57,192		524,412		(55,060)		253,124
Income tax provision (benefit)	204,007		24,017		31,901		6,795		(7,461)	[6],[7]	(4,113)		(7,271)		7,206		266,720		(11,639)		46,647
Net income (loss)	$ (105,923)		$ 103,420		$ 174,976		$ 85,221		$ 66,345	[6],[7]	$ 63,794		$ (223,546)		$ 49,986		$ 257,692		$ (43,421)		$ 206,477
Net income (loss) per common share:
Basic	$ (0.54)		$ 0.52		$ 0.88		$ 0.43		$ 0.33	[6],[7]	$ 0.32		$ (1.10)		$ 0.24		$ 1.30		$ (0.21)		$ 0.98
Diluted	(0.54)		0.52		0.87		0.42		0.33	[6],[7]	0.31		(1.10)		0.24		$ 1.28		$ (0.21)		$ 0.97
Weighted average common shares-basic																	198,069		202,578		211,544
Weighted average common shares-diluted																	201,641		202,578		213,321
Cash dividend declared per common share	$ 0.07		$ 0.07		$ 0.07		$ 0.07		$ 0.06	[6],[7]	$ 0.06		$ 0.06		$ 0.06		$ 0.28		$ 0.24		$ 0.24
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[11]	Revenues attributable to a country are based on location of customer site.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 257,692	$ (43,421)	$ 206,477
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of $0, $0, $0	37,840	(13,162)	(8,759)
Available-for-sale marketable securities:
Unrealized gains (losses) on marketable securities arising during period, net of tax of $1,903, $923, $(1,667), respectively	1,863	2,037	(3,075)
Less: Reclassification adjustment for gains included in net income (loss), net of tax of $(297), $(255), $(390), respectively	(441)	(683)	(704)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total	1,422	1,354	(3,779)
Defined benefit pension and post-retirement plans:
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $(154), $(190), $(169), respectively	(272)	(321)	(295)
Prior service income arising during period, net of tax of $0, $34, $0, respectively		59
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(272)	(262)	(295)
Other comprehensive income (loss)	38,990	(12,070)	(12,833)
Comprehensive income (loss)	$ 296,682	$ (55,491)	$ 193,644

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0
Unrealized gains (losses) on marketable securities arising during period, tax	1,903	923	(1,667)
Reclassification adjustment for gains included in net income (loss), tax	(297)	(255)	(390)
Amortization of net prior service (credit) cost included in net periodic pension and post-retirement expense/income, tax	(154)	(190)	(169)
Prior service credit, tax	$ 0	$ 34	$ 0

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance, at Dec. 31, 2014	$ 2,078,980	$ 27,077	$ 1,437,135	$ 4,689	$ 610,079
Balance, Shares at Dec. 31, 2014		216,613
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)		2,649
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	8,933	$ 331	8,602
Stock-based compensation expense	30,285		30,285
Repurchase of common stock	$ (299,949)	$ (1,953)			(297,996)
Repurchase of common stock (in shares)	(15,600)	(15,621)
Tax benefit related to stock options and restricted stock units	$ 4,625		4,625
Cash dividends	(50,732)				(50,732)
Net income (loss)	206,477				206,477
Foreign currency translation adjustment	(8,759)			(8,759)
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), 923, 1903 respectively	(3,075)			(3,075)
Less: reclassification adjustment for gains included in net income, net of tax $(390), (255), (297) respectively	(704)			(704)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $$(169), $(190), (154) respectively	(295)			(295)
Balance, at Dec. 31, 2015	1,965,786	$ 25,455	1,480,647	(8,144)	467,828
Balance, Shares at Dec. 31, 2015		203,641
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)		2,377
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	10,665	$ 297	10,368
Equity component of convertible debt	100,836		100,836
Equity component of convertible notes issuance cost	(2,017)		(2,017)
Purchase of convertible notes hedges	(100,834)		(100,834)
Proceeds from issuance of warrants	67,852		67,852
Stock-based compensation expense	30,745		30,745
Repurchase of common stock	$ (146,331)	$ (855)			(145,476)
Repurchase of common stock (in shares)	(6,800)	(6,841)
Tax benefit related to stock options and restricted stock units	$ 6,087		6,087
Cash dividends	(48,639)				(48,639)
Net income (loss)	(43,421)				(43,421)
Foreign currency translation adjustment	(13,162)			(13,162)
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), 923, 1903 respectively	2,037			2,037
Less: reclassification adjustment for gains included in net income, net of tax $(390), (255), (297) respectively	(683)			(683)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $$(169), $(190), (154) respectively	(321)			(321)
Prior service income arising during period, net of tax of $34	59			59
Balance, at Dec. 31, 2016	1,828,659	$ 24,897	1,593,684	(20,214)	230,292
Balance, Shares at Dec. 31, 2016		199,177
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax (in shares)		2,211
Issuance of stock to employees under benefit plans, net of shares withheld for payroll tax	11,024	$ 277	10,747
Stock-based compensation expense	33,982		33,982
Repurchase of common stock	(200,304)	$ (730)			(199,574)
Repurchase of common stock (in shares)		(5,840)
Cumulative effect adjustment for prior year tax benefits related to stock options and restricted stock units	39,081				39,081
Cash dividends	(55,478)				(55,478)
Net income (loss)	257,692				257,692
Foreign currency translation adjustment	37,840			37,840
Unrealized gains (losses) on marketable securities:
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(1,667), 923, 1903 respectively	1,863			1,863
Less: reclassification adjustment for gains included in net income, net of tax $(390), (255), (297) respectively	(441)			(441)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, net of tax $$(169), $(190), (154) respectively	(272)			(272)
Balance, at Dec. 31, 2017	$ 1,953,646	$ 24,444	$ 1,638,413	$ 18,776	$ 272,013
Balance, Shares at Dec. 31, 2017		195,548

CONSOLIDATED STATEMENTS OF SHA8

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Issuance of stock to employees under benefit plans, shares withheld for payroll tax	$ 12,881	$ 9,398	$ 10,235
Unrealized (losses) gains on marketable securities arising during period, tax	1,903	923	(1,667)
Reclassification adjustment for gains included in net income, tax	(297)	(255)	(390)
Amortization of prior service (credit) cost included in net periodic pension and post-retirement expense/income, tax	(154)	(190)	(169)
Prior service income arising during period, tax	$ 0	$ 34	$ 0

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ 257,692	$ (43,421)	$ 206,477
Adjustments to reconcile net income (loss) from operations to net cash provided by operating activities:
Depreciation	66,122	64,782	68,181
Amortization	41,953	55,227	72,592
Stock-based compensation	34,097	30,750	30,451
Deferred taxes	37,105	(62,936)	(7,124)
Provision for excess and obsolete inventory	8,844	17,493	21,332
Contingent consideration fair value adjustment	7,820	15,896	2,489
Retirement plans actuarial (gains) losses	(6,624)	(3,203)	17,732
Property insurance recovery, net	(4,309)
Goodwill impairment	0	254,946
Acquired intangible assets impairment		83,339
Tax benefit related to employee stock compensation awards		(6,198)	(4,715)
Gain from the sale of an equity investment			(5,406)
Non-cash charge for the sale of inventories revalued at the date of acquisition			1,567
Other	707	(448)	(34)
Changes in operating assets and liabilities, net of businesses acquired:
Accounts receivable	(80,584)	18,325	(57,267)
Inventories	44,960	34,263	15,559
Prepayments and other assets	2,254	(19,194)	3,034
Accounts payable and other accrued expenses	43,574	6,820	58,448
Deferred revenue and customer advances	4,984	(3,634)	17,011
Retirement plan contributions	(5,902)	(6,044)	(12,095)
Income taxes	173,802	18,434	(5,156)
Net cash provided by operating activities	626,495	455,197	423,076
Cash flows from investing activities:
Purchases of property, plant and equipment	(105,375)	(85,272)	(89,878)
Purchases of available-for-sale marketable securities	(1,391,917)	(1,656,267)	(1,424,002)
Proceeds from maturities of available-for-sale marketable securities	701,681	243,232	360,264
Proceeds from sales of available-for-sale marketable securities	527,746	852,794	1,316,131
Proceeds from property insurance	5,064	5,051
Acquisition of businesses, net of cash acquired			(282,741)
Proceeds from life insurance			1,098
Proceeds from the sale of an equity investment			5,406
Net cash used for investing activities	(262,801)	(640,462)	(113,722)
Cash flows from financing activities:
Issuance of common stock under stock purchase and stock option plans	24,493	20,473	19,530
Repurchase of common stock	(200,304)	(146,331)	(299,949)
Dividend payments	(55,447)	(48,619)	(50,713)
Payments related to net settlement of employee stock compensation awards	(12,881)	(9,398)	(10,235)
Payments of contingent consideration	(1,050)	(11,697)
Proceeds from issuance of convertible notes, net of issuance costs		450,800
Purchase of convertible note hedges		(100,834)
Proceeds from issuance of warrants		67,852
Tax benefit related to employee stock compensation awards		6,198	4,715
Payment of revolving credit facility costs			(2,253)
Net cash (used for) provided by financing activities	(245,189)	228,444	(338,905)
Effects of exchange rate changes on cash and cash equivalents	3,454
Increase (decrease) in cash and cash equivalents	121,959	43,179	(29,551)
Cash and cash equivalents at beginning of year	307,884	264,705	294,256
Cash and cash equivalents at end of year	429,843	307,884	264,705
Cash paid for:
Interest	6,446	446	301
Income taxes	$ 53,775	$ 40,424	$ 35,218

The Company

The Company	12 Months Ended
	Dec. 31, 2017
The Company	A. THE COMPANY Teradyne, Inc. (“Teradyne”) is a leading global supplier of automation equipment for test and industrial applications. Teradyne designs, develops, manufactures and sells automatic test systems used to test semiconductors, wireless products, data storage and complex electronics systems in the consumer electronics, wireless, automotive, industrial, computing, communications, and aerospace and defense industries. Teradyne’s industrial automation products include collaborative robots used by global manufacturing and light industrial customers to improve quality, increase manufacturing efficiency and decrease manufacturing costs. Teradyne’s automatic test equipment and industrial automation products and services include: • semiconductor test (“Semiconductor Test”) systems; • defense/aerospace (“Defense/Aerospace”) test instrumentation and systems, storage test (“Storage Test”) systems, and circuit-board test and inspection (“Production Board Test”) systems (collectively these products represent “System Test”); • industrial automation (“Industrial Automation”) products; and • wireless test (“Wireless Test”) systems. On June 11, 2015, Teradyne acquired Universal Robots A/S (“Universal Robots”) for approximately $284 million of cash plus up to an additional $65 million of cash if certain performance targets are met extending through 2018. Universal Robots is the leading supplier of collaborative robots which are low-cost, easy-to-deploy simple-to-program

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies	B. ACCOUNTING POLICIES The consolidated financial statements include the accounts of Teradyne and its wholly-owned subsidiaries. All significant intercompany balances and transactions are eliminated. Certain prior years’ amounts were reclassified to conform to the current year presentation. Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going Revenue Recognition Teradyne recognizes revenues, including revenues from distributors, when there is persuasive evidence of an arrangement, title and risk of loss have passed, delivery has occurred or the services have been rendered, the sales price is fixed or determinable and collection of the related receivable is reasonably assured. Title and risk of loss generally pass to Teradyne’s customers upon shipment or at delivery destination point. In circumstances where either title or risk of loss pass upon destination, acceptance or cash payment, Teradyne defers revenue recognition until such events occur except when title transfer is tied to cash payment outside the United States. Outside the United States, Teradyne recognizes revenue upon shipment or at delivery destination point, even if Teradyne retains a form of title to products delivered to customers, provided the sole purpose is to enable Teradyne to recover the products in the event of customer payment default and the arrangement does not prohibit the customer’s use or resale of the product in the ordinary course of business. Teradyne’s equipment has non-software For multiple element arrangements, Teradyne allocates revenue to all deliverables based on their relative selling prices. In such circumstances, a hierarchy is used to determine the selling price for allocating revenue to deliverables as follows: (i) vendor-specific objective evidence of selling price (“VSOE”), (ii) third-party evidence of selling price (“TPE”), and (iii) best estimate of the selling price (“BESP”). For a delivered item to be considered a separate unit the delivered item must have value to the customer on a standalone basis and the delivery or performance of the undelivered item must be considered probable and substantially in Teradyne’s control. Teradyne’s post-shipment obligations include installation, training services, one-year 605-20, Separately Priced Extended Warranty and Product Maintenance Contracts 605-25, Revenue Recognition Multiple-Element Arrangements. Teradyne’s products are generally subject to warranty and related costs of the warranty are provided for in cost of revenues when product revenue is recognized. Teradyne classifies shipping and handling costs in cost of revenue. Teradyne does not provide its customers with contractual rights of return for any of its products. As of December 31, 2017 and 2016, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2017 2016 (in thousands) Maintenance and training $ 57,256 $ 46,803 Customer advances, undelivered elements and other 32,047 32,938 Extended warranty 24,438 28,200 Total deferred revenue and customer advances $ 113,741 $ 107,941 Product Warranty Teradyne generally provides a one-year Amount (in thousands) Balance at December 31, 2014 $ 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 6,925 Accruals for warranties issued during the period 14,291 Accruals related to pre-existing (1,354 ) Settlements made during the period (12,659 ) Balance at December 31, 2016 7,203 Accruals for warranties issued during the period 14,223 Accruals related to pre-existing (379 ) Settlements made during the period (12,847 ) Balance at December 31, 2017 $ 8,200 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2014 $ 34,197 Acquisition 870 Deferral of new extended warranty revenue 17,698 Recognition of extended warranty deferred revenue (22,741 ) Balance at December 31, 2015 30,024 Deferral of new extended warranty revenue 19,909 Recognition of extended warranty deferred revenue (21,733 ) Balance at December 31, 2016 28,200 Deferral of new extended warranty revenue 20,513 Recognition of extended warranty deferred revenue (24,275 ) Balance at December 31, 2017 $ 24,438 Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The volatility of the industries that Teradyne serves can cause certain of its customers to experience shortages of cash flows, which can impact their ability to make required payments. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered. Inventories Inventories are stated at the lower of cost (first-in, first-out Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, Investments—Debt and Equity Securities 320-10 available-for-sale held-to-maturity • The length of time and the extent to which the market value has been less than cost; • The financial condition and near-term prospects of the issuer; and • The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. As defined in ASC 820-10, Fair Value Measurements and Disclosures, ASC 820-10 Level 1: Quoted prices in active markets for identical assets as of the reporting date. Level 2: Inputs other than Level 1, that are observable either directly or indirectly as of the reporting date. For example, a common approach for valuing fixed income securities is the use of matrix pricing. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and therefore is considered a Level 2 input. Level 3: Unobservable inputs that are not supported by market data. Unobservable inputs are developed based on the best information available, which might include Teradyne’s own data. In accordance with ASC 820-10, Prepayments Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2017 2016 (in thousands) Contract manufacturer and supplier prepayments $ 82,503 $ 84,473 Prepaid maintenance and other services 8,189 7,676 Prepaid taxes 5,039 4,664 Other prepayments 12,386 11,641 Total prepayments $ 108,117 $ 108,454 Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, Intangibles-Goodwill and Other. 350-10, more-likely-than-not two-step more-likely-than-not two-step In accordance with ASC 360-10, Impairment or Disposal of Long-Lived Assets, Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees including non-recurring Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, Compensation-Stock Compensation In March 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-09, “Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” Adoption of this ASU required recognition of a cumulative effect adjustment to retained earnings for any prior year excess tax benefits or tax deficiencies not previously recorded. The cumulative effect adjustment of $39 million was recorded in the first quarter of 2017 as an increase to retained earnings and deferred tax assets. This ASU also required a change in how Teradyne recognizes the excess tax benefits or tax deficiencies related to stock-based compensation. Prior to adopting ASU 2016-09, paid-in 2016-09, ASU 2016-09 In addition, under ASU 2016-09, Upon adoption of ASU 2016-09, Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.” tax-planning Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $9.1 million, $6.4 million, and $3.3 million in 2017, 2016, and 2015, respectively. Translation of Non-U.S. The functional currency for all subsidiaries is the U.S. dollar, except for the Industrial Automation segment for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For the years ended December 31, 2017, 2016, and 2015, losses (gains) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.9 million, $(8.0) million, and $(2.5) million, respectively. These amounts do not reflect the corresponding (gains) losses from foreign exchange contracts. See Note G: “Financial Instruments” regarding foreign exchange contracts. Net Income (Loss) per Common Share Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Except where the result would be antidilutive, diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. With respect to its convertible debt issued in 2016, Teradyne has determined that it has the ability and intent to settle the principal of the convertible debt in cash; accordingly, the principal amount is excluded from the determination of diluted earnings per share. As a result, Teradyne is accounting for the conversion spread using the treasury stock method. Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt and equity marketable securities and foreign currency translation adjustment.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Recently Issued Accounting Pronouncements	C. RECENTLY ISSUED ACCOUNTING PRONOUNCEMENTS On February 15, 2018, the FASB issued ASU 2018-02, “Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” On March 10, 2017, the FASB issued ASU 2017-07, “Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost On January 26, 2017, the FASB issued ASU 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment.” one-step In October 2016, the FASB issued ASU 2016-16, “Accounting for Income Taxes: Intra-Entity Asset Transfers of Assets Other than Inventory ” pre-tax In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” “Leases.” right-of-use In January 2016, the FASB issued ASU 2016-01, “Financial Instruments—Overall (Subtopic 825-10): ” In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” 2015-14,

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2017
Acquisitions	D. ACQUISITIONS Business Universal Robots On June 11, 2015, Teradyne acquired all of the outstanding equity of Universal Robots located in Odense, Denmark. Universal Robots is the leading supplier of collaborative robots which are low-cost, easy-to-deploy simple-to-program earn-out The Universal Robots acquisition was accounted for as a business combination and, accordingly, the results have been included in Teradyne’s consolidated results of operations from the date of acquisition. The allocation of the total purchase price to Universal Robots’ net tangible liabilities and identifiable intangible assets was based on their estimated fair values as of the acquisition date. The excess of the purchase price over the identifiable intangible assets and net tangible liabilities in the amount of $221.1 million was allocated to goodwill, which is not deductible for tax purposes. The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 221,128 Intangible assets 121,590 Tangible assets acquired and liabilities assumed: Current assets 10,853 Non-current 3,415 Accounts payable and current liabilities (11,976 ) Long-term deferred tax liabilities (26,653 ) Long-term other liabilities (2,920 ) Total purchase price $ 315,437 Teradyne estimated the fair value of intangible assets using the income and cost approaches. Acquired intangible assets are amortized on a straight-line basis over their estimated useful lives. Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 89,240 4.9 Trademarks and tradenames 22,920 10.0 Customer relationships 9,430 2.0 Total intangible assets $ 121,590 5.6 For the period from June 12, 2015 to December 31, 2015, Universal Robots contributed $41.9 million of revenues and had a $7.6 million loss before income taxes. The following unaudited pro forma information gives effect to the acquisition of Universal Robots as if the acquisition occurred on January 1, 2014. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, 2015 (in thousands, except per share amounts) Revenue $ 1,657,626 Net income $ 199,784 Net income per common share: Basic $ 0.94 Diluted $ 0.94 Pro forma results for the year ended December 31, 2015 were adjusted to exclude $1.6 million of non-recurring

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventories	E. INVENTORIES Inventories, net consisted of the following at December 31, 2017 and 2016: 2017 2016 (in thousands) Raw material $ 62,668 $ 58,530 Work-in-process 19,464 22,946 Finished Goods 25,393 54,482 $ 107,525 $ 135,958 Inventory reserves for the years ended December 31, 2017 and 2016 were $102.9 million and $116.0 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment	F. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment, net consisted of the following at December 31, 2017 and 2016: 2017 2016 (in thousands) Land $ 16,561 $ 16,561 Buildings 98,369 98,031 Machinery and equipment 647,961 601,835 Furniture and fixtures, and software 88,539 82,897 Leasehold improvements 49,540 46,612 Construction in progress 13,522 3,032 914,492 848,968 Less: accumulated depreciation 646,045 595,147 $ 268,447 $ 253,821 Depreciation of property, plant and equipment for the years ended December 31, 2017, 2016, and 2015 was $66.1 million, $64.8 million, and $68.2 million, respectively. As of December 31, 2017 and 2016, the gross book value included in machinery and equipment for internally manufactured test systems being leased by customers was $18.1 million and $19.4 million, respectively. As of December 31, 2017 and 2016, the accumulated depreciation on these test systems was $13.7 million and $10.5 million, respectively.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2017
Financial Instruments	G. 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 Realized gains recorded in 2017, 2016, and 2015 were $1.1 million, $1.6 million, and $1.7 million, respectively. Realized losses recorded in 2017, 2016, and 2015 were $0.3 million, $0.5 million, and $0.4 million, respectively. Realized gains are included in interest income, and realized losses are included in interest expense. Unrealized gains and losses are included in accumulated other comprehensive income (loss). The cost of securities sold is based on the specific identification method. During the years ended December 31, 2017 and 2016, there were no transfers in or out of Level 1, Level 2 or Level 3 financial instruments. The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2017 and 2016: December 31, 2017 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 197,955 $ — $ — $ 197,955 Cash equivalents 206,335 25,553 — 231,888 Available for sale securities: U.S. Treasury securities — 855,795 — 855,795 Commercial paper — 282,840 — 282,840 Certificates of deposit and time deposits — 167,342 — 167,342 Corporate debt securities — 133,186 — 133,186 Equity and debt mutual funds 23,430 — — 23,430 U.S. government agency securities — 10,726 — 10,726 Non-U.S. — 586 — 586 $ 427,720 $ 1,476,028 $ — $ 1,903,748 Derivative assets — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Contingent consideration $ — $ — $ 45,102 $ 45,102 Derivative liabilities — 446 — 446 Total $ — $ 446 $ 45,102 $ 45,548 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 404,290 $ 25,553 $ — $ 429,843 Marketable securities — 1,347,979 — 1,347,979 Long-term marketable securities 23,430 102,496 — 125,926 Prepayments — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Other current liabilities $ — $ 446 $ — $ 446 Contingent consideration — — 24,497 24,497 Long-term contingent consideration — — 20,605 20,605 Total $ — $ 446 $ 45,102 $ 45,548 December 31, 2016 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 $ 214,722 $ — $ — $ 214,722 Cash equivalents 37,458 55,704 — 93,162 Available for sale securities: U.S. Treasury securities — 902,800 — 902,800 Commercial paper — 161,630 — 161,630 Corporate debt securities — 100,153 — 100,153 Certificates of deposit and time deposits — 82,133 — 82,133 U.S. government agency securities — 39,252 — 39,252 Equity and debt mutual funds 18,171 — — 18,171 Non-U.S. — 728 — 728 $ 270,351 $ 1,342,400 $ — $ 1,612,751 Derivative assets — 1 — 1 Total $ 270,351 $ 1,342,401 $ — $ 1,612,752 Liabilities Contingent consideration $ — $ — $ 38,332 $ 38,332 Derivative liabilities — 131 — 131 Total $ — $ 131 $ 38,332 $ 38,463 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 252,180 $ 55,704 $ — $ 307,884 Marketable securities — 871,024 — 871,024 Long-term marketable securities 18,171 415,672 — 433,843 Prepayments — 1 — 1 Total $ 270,351 $ 1,342,401 $ — $ 1,612,752 Liabilities Other current liabilities $ — $ 131 $ — $ 131 Contingent consideration — — 1,050 1,050 Long-term contingent consideration — — 37,282 37,282 Total $ — $ 131 $ 38,332 $ 38,463 Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2017 and 2016 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2015 $ 37,436 Payments (1) (15,000 ) Fair value adjustment of AIT (2) 550 Fair value adjustment of Universal Robots (2) 15,346 Balance at December 31, 2016 38,332 Payments (3) (1,050 ) Fair value adjustment of Universal Robots (4) 7,820 Balance at December 31, 2017 $ 45,102 (1) During the year ended December 31, 2016, based on Universal Robots’ calendar year 2015 EBITDA results, Teradyne paid $15 million or 100% of the eligible EBITDA contingent consideration amount. (2) During the year ended December 31, 2016, the fair value of contingent consideration for the earn-out earn-out (3) During the year ended December 31, 2017, Teradyne paid $1.1 million of contingent consideration for the earn-out (4) During the year ended December 31, 2017, the fair value of contingent consideration for the earn-out The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (Universal Robots) $ 24,497 (1) $ 20,605 Monte Carlo simulation Revenue for the period July 1, 2015—December 31, 2018 volatility 11.2% Discount Rate 3.3% (1) Contingent consideration of $24.5 million is expected to be paid in March 2018. As of December 31, 2017, the significant unobservable inputs used in the Monte Carlo simulation to fair value the Universal Robots contingent consideration include forecasted revenues, revenue volatility and discount rate. Increases or decreases in the inputs would result in a higher or lower fair value measurement. The maximum payment for the remaining Universal Robots earn-out The carrying amounts and fair values of financial instruments at December 31, 2017 and 2016 were as follows: December 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 429,843 $ 429,843 $ 307,884 $ 307,884 Marketable securities 1,473,905 1,473,905 1,304,867 1,304,867 Derivative assets 389 389 1 1 Liabilities Contingent consideration 45,102 45,102 38,332 38,332 Derivative liabilities 446 446 131 131 Convertible debt (1) 365,987 659,525 352,669 486,754 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features. The fair values of accounts receivable, net and accounts payable approximate the carrying amount due to the short term nature of these instruments. The following tables summarize the composition of available for sale marketable securities at December 31, 2017 and 2016: December 31, 2017 Available-for-Sale Fair Market Value of Investments with Unrealized Losses Cost Unrealized Gain Unrealized (Loss) Fair Market Value (in thousands) U.S. Treasury securities $ 858,258 $ 72 $ (2,535 ) $ 855,795 $ 850,163 Commercial paper 283,009 18 (187 ) 282,840 258,933 Certificates of deposit and time deposits 167,523 6 (187 ) 167,342 138,340 Corporate debt securities 131,179 2,380 (373 ) 133,186 91,010 Equity and debt mutual funds 19,403 4,102 (75 ) 23,430 1,723 U.S. government agency securities 10,775 — (49 ) 10,726 10,726 Non-U.S. 582 4 — 586 — $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 1,349,970 $ 38 $ (2,029 ) $ 1,347,979 $ 1,288,844 Long-term marketable securities 120,759 6,544 (1,377 ) 125,926 62,052 $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 December 31, 2016 Available-for-Sale Fair Market Value of Investments with Unrealized Losses Cost Unrealized Gain Unrealized (Loss) Fair Market Value (in thousands) U.S. Treasury securities $ 904,737 $ 97 $ (2,034 ) $ 902,800 $ 572,284 Commercial paper 161,672 24 (66 ) 161,630 84,034 Corporate debt securities 99,708 1,065 (620 ) 100,153 53,642 Certificates of deposit and time deposits 82,080 54 (1 ) 82,133 7,760 U.S. government agency securities 39,264 7 (19 ) 39,252 13,461 Equity and debt mutual funds 16,505 1,724 (58 ) 18,171 1,661 Non-U.S. 745 6 (23 ) 728 137 $ 1,304,711 $ 2,977 $ (2,821 ) $ 1,304,867 $ 732,979 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 871,321 $ 134 $ (431 ) $ 871,024 $ 423,128 Long-term marketable securities 433,390 2,843 (2,390 ) 433,843 309,851 $ 1,304,711 $ 2,977 $ (2,821 ) $ 1,304,867 $ 732,979 As of December 31, 2017, the fair market value of investments with unrealized losses totaled $1,350.9 million. Of this value, $141.0 million had unrealized losses of $1.2 million greater than one year and $1,209.9 million had unrealized losses of $2.2 million for less than one year. As of December 31, 2016, the fair market value of investments with unrealized losses totaled $733.0 million. Of this value, $2.9 million had unrealized losses of $0.3 million greater than one year and $730.1 million had unrealized losses of $2.5 million for less than one year. Teradyne reviews its investments to identify and evaluate investments that have an indication of possible impairment. Based on this review, Teradyne determined that the unrealized losses related to these investments, at December 31, 2017 and 2016, were temporary. The contractual maturities of investments held at December 31, 2017 were as follows: Cost Fair Value (in thousands) Due within one year $ 1,349,970 $ 1,347,979 Due after 1 year through 5 years 48,796 48,599 Due after 5 years through 10 years 13,916 13,489 Due after 10 years 38,644 40,408 Total $ 1,451,326 $ 1,450,475 Contractual maturities of investments held at December 31, 2017 exclude $23.4 million of equity and debt mutual funds as they do not have a contractual maturity date. The following table sets forth by fair value hierarchy Teradyne’s non-financial non-recurring July 3, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total Total (in thousands) Assets Goodwill $ — $ — $ 7,976 $ 7,976 $ 254,946 Definite lived intangible assets — — 5,750 5,750 83,339 $ — $ — $ 13,726 $ 13,726 $ 338,285 (1) In accordance with the provisions of ASC 350-20, Goodwill (2) In accordance with the provisions of ASC 360-10, “Property, Plant and Equipment”, Derivatives Teradyne conducts business in a number of foreign countries, with certain transactions denominated in local currencies. The purpose of Teradyne’s foreign currency management is to minimize the effect of exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities. Teradyne does not use derivative financial instruments for trading or speculative purposes. To minimize the effect of exchange rate fluctuations associated with the remeasurement of monetary assets and liabilities denominated in foreign currencies, Teradyne enters into foreign currency forward contracts. The change in fair value of these derivatives is recorded directly in earnings, and is used to offset the change in value of the monetary assets and liabilities denominated in foreign currencies. At December 31, 2017 and 2016, Teradyne had the following contracts to buy and sell non-U.S. non-U.S. December 31, 2017 December 31, 2016 Buy Position Sell Position Net Total Buy Position Sell Position Net Total (in millions) Japanese Yen $ (35.7 ) $ — $ (35.7 ) $ (17.7 ) $ — $ (17.7 ) Taiwan Dollar (9.9 ) — (9.9 ) (6.9 ) — (6.9 ) Korean Won (8.9 ) — (8.9 ) (8.8 ) — (8.8 ) British Pound Sterling (1.4 ) — (1.4 ) (1.3 ) — (1.3 ) Singapore Dollar — 33.5 33.5 — 24.0 24.0 Euro — 27.4 27.4 — 25.2 25.2 Total $ (55.9 ) $ 60.9 $ 5.0 $ (34.7 ) $ 49.2 $ 14.5 The fair value of the outstanding contracts was a loss of $0.1 million, at December 31, 2017 and 2016. Gains and losses on foreign currency forward contracts and foreign currency remeasurement gains and losses on monetary assets and liabilities are included in other (income) expense, net. The following table summarizes the fair value of derivative instruments as of December 31, 2017 and 2016: Balance Sheet Location 2017 2016 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 389 $ 1 Foreign exchange contracts Other current liabilities (446 ) (131 ) Total derivatives $ (57 ) $ (130 ) The following table summarizes the effect of derivative instruments in the statements of operations recognized for the years ended December 31, 2017, 2016, and 2015. Location of (Gains) Losses Recognized in Statement of Operations 2017 2016 2015 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ (1,133 ) $ 8,671 $ 3,047 (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 year ended December 31, 2017, net losses from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $2.9 million. (3) For the years ended December 31, 2016, and 2015, net gains from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $8.0 million and $2.5 million, respectively. See Note H: “Debt” regarding derivatives related to the convertible senior notes. Concentration of Credit Risk Financial instruments which potentially subject Teradyne to concentrations of credit risk consist principally of cash equivalents, marketable securities, forward currency contracts and accounts receivable. Teradyne’s cash equivalents consist primarily of money market funds invested in U.S. Treasuries and government agencies. Teradyne’s fixed income available-for-sale Equity Interest On November 1, 2013, in connection with the acquisition of Empirix, Inc. by Thoma Bravo LLC, Teradyne sold its equity interest in Empirix, Inc., a private company, and received cash proceeds of $34.2 million which was recorded as a gain in other (income) expense, net in the fourth quarter of 2013. An additional $5.4 million of cash proceeds that was held in escrow for 15 months, for potential indemnifications to the buyer, was paid to Teradyne in February 2015 and it was recorded as a gain in other (income) expense, net in the first quarter of 2015.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt	H. 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% per year payable semiannually in arrears on June 15 and December 15 of each year, beginning on June 15, 2017. The Notes will be convertible at the option of the noteholders at any time prior to the close of business on the business day immediately preceding September 15, 2023, only under the following circumstances: (1) during any calendar quarter beginning after March 31, 2017 (and only during such calendar quarter), if the closing sale price of Teradyne’s common stock, for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price (as defined in the Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the closing sale price of the Teradyne’s common stock and the conversion rate on each such trading day; and (3) upon the occurrence of specified corporate events. On or after September 15, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. Teradyne may satisfy its conversion obligation by paying or delivering cash, shares of its common stock or a combination of cash and shares of its common stock, at Teradyne’s election. As of December 31, 2017, the conversion price was approximately $31.80 per share of Teradyne’s common stock. The conversion rate is subject to adjustment under certain circumstances. Concurrent with the offering of the Notes, Teradyne entered into convertible note hedge transactions (the “Note Hedge Transactions”) with the initial purchasers or their affiliates (the “Option Counterparties”). The Note Hedge Transactions cover, subject to customary anti-dilution adjustments, the number of shares of the common stock that underlie the Notes, with a strike price equal to the conversion price of the Notes of $31.80. The Note Hedge Transactions cover, subject to customary antidilution adjustments, approximately 14.5 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 The below tables represents the key components of Teradyne’s convertible senior notes: December 31, 2017 December 31, (in thousands) (in thousands) Debt Principal $ 460,000 $ 460,000 Unamortized discount 94,013 107,331 Net Carrying amount of convertible debt $ 365,987 $ 352,669 For the year ended December 31, December 31, (in thousands) (in thousands) Contractual interest expense on the coupon $ 5,734 $ 303 Amortization of the discount component and debt issue fees recognized as interest expense 13,318 688 Total interest expense on the convertible debt $ 19,052 $ 991 As of December 31, 2017, the unamortized discount was $94.0 million, which will be amortized over six years using the effective interest rate method. The carrying amount of the equity component was $100.8 million. As of December 31, 2017, the conversion price was approximately $31.80 per share and if converted value of the notes was $605.7 million. Revolving Credit Facility On April 27, 2015, Teradyne entered into a Credit Agreement (the “Credit Agreement”) with Barclays Bank PLC, as administrative agent and collateral agent, and the lenders party thereto. The Credit Agreement provides for a five-year, senior secured revolving credit facility of up to $350 million (the “Credit Facility”). The Credit Agreement further provides that, subject to customary conditions, Teradyne may seek to obtain from existing or new lenders incremental commitments under the Credit Facility in an aggregate principal amount not to exceed $150 million. Proceeds from the Credit Facility may be used for general corporate purposes and working capital. Teradyne incurred $2.3 million in costs related to the revolving credit facility. These costs are being amortized over the five-year term of the revolving credit facility and are included in interest expense in the statements of operations. As of March 1, 2018, Teradyne has not borrowed any funds under the Credit Facility. The interest rates applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.00% to 1.00% per annum or LIBOR plus a margin ranging from 1.00% to 2.00% per annum, based on the Consolidated Leverage Ratio of Teradyne and its Restricted Subsidiaries. In addition, Teradyne will pay a commitment fee on the unused portion of the commitments under the Credit Facility ranging from 0.125% to 0.350% per annum, based on the then applicable Consolidated Leverage Ratio. Teradyne is not required to repay any loans under the Credit Facility prior to maturity, subject to certain customary exceptions. Teradyne is permitted to prepay all or any portion of the loans under the Credit Facility prior to maturity without premium or penalty, other than customary LIBOR breakage costs. The Credit Agreement contains customary events of default, representations, warranties and affirmative and negative covenants that, among other things, limit Teradyne’s and its Restricted Subsidiaries’ ability to sell assets, grant liens on assets, incur other secured indebtedness and make certain investments and restricted payments, all subject to exceptions set forth in the Credit Agreement. The Credit Agreement also requires Teradyne to satisfy two financial ratios measured as of the end of each fiscal quarter: a consolidated leverage ratio and an interest coverage ratio. As of December 31, 2017, Teradyne was in compliance with all covenants. The Credit Facility is guaranteed by certain of Teradyne’s domestic subsidiaries and collateralized by assets of Teradyne and such subsidiaries, including a pledge of 65% of the capital stock of certain foreign subsidiaries.

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive (Loss) Income	I. ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME Changes in accumulated other comprehensive (loss) income, which is presented net of tax, consists of the following: Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Balance at December 31, 2015, net of tax of $0, (459), $(622) $ (8,759 ) $ (1,414 ) $ 2,029 $ (8,144 ) Other comprehensive (loss) income before reclassifications, net of tax of $0, $923, $34 (13,162 ) 2,037 59 (11,066 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(255), $(190) — (683 ) (321 ) (1,004 ) Net current period other comprehensive (loss) income, net of tax of $0, $668, $(156) (13,162 ) 1,354 (262 ) (12,070 ) Balance at December 31, 2016, net of tax of $0, $209, $(778) (21,921 ) (60 ) 1,767 (20,214 ) Other comprehensive income before reclassifications, net of tax of $0, $1,903, $0 37,840 1,863 — 39,703 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(297), $(154) — (441 ) (272 ) (713 ) Net current period other comprehensive income, net of tax of $0, $1,606, $(154) 37,840 1,422 (272 ) 38,990 Balance at December 31, 2017, net of tax of $0, $1,815, $(932) $ 15,919 $ 1,362 $ 1,495 $ 18,776 Reclassifications out of accumulated other comprehensive income to the statements of operations for the years ended December 31, 2017, 2016 and 2015, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item in the Statements of Operations December 31, 2017 December 31, 2016 December 31, 2015 (in thousands) Available-for-sale Unrealized gains, net of tax of $297, $255, $390 $ 441 $ 683 $ 704 Interest income Defined benefit pension and postretirement plans: Amortization of prior service benefit, net of tax of $154, $190, $169 272 321 295 (a) Total reclassifications, net of tax of $451, $445, $559 $ 713 $ 1,004 $ 999 Net income (a) The amortization of prior service credit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: “Retirement Plans.”

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets	J. GOODWILL AND INTANGIBLE ASSETS Goodwill Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, Intangibles—Goodwill and Other, Teradyne has the option to perform a qualitative assessment (“Step zero”) to determine whether it is more-likely-than-not two-step more-likely-than-not two-step two-step In the second quarter of 2016, the Wireless Test reporting unit (which is Teradyne’s Wireless Test operating and reportable segment) reduced headcount by 11% as a result of a sharp decline in projected demand attributable to an estimated smaller future wireless test market. The decrease in projected demand was due to lower forecasted buying from Teradyne’s largest Wireless Test segment customer (who has contributed between 51% and 73% of annual Wireless Test sales since the LitePoint acquisition in 2011 through 2015) as a result of the customer’s numerous operational efficiencies; slower smartphone growth rates; and a slowdown of new wireless technology adoption. Teradyne considered the headcount reduction and sharp decline in projected demand to be a triggering event for an interim goodwill impairment test. Teradyne allocated the fair value of the Wireless Test reporting unit to all of its assets and liabilities (including unrecognized intangible assets). The net book value of raw materials inventory was estimated as an approximation of current replacement costs. The fair value of finished goods inventory was estimated at the present value of selling price less direct selling costs and profit on the selling effort. The selling price used in the inventory fair values was based upon the product gross margins included in Teradyne’s forecast. The fair value of the deferred revenue liability was estimated by assessing the costs required to service the obligation plus a reasonable profit margin. The fair value for personal property assets, which consisted of furniture and fixtures, machinery and equipment, computer equipment, software and leasehold improvements, was estimated using the replacement cost approach, which approximated carrying value. The fair value of intangible assets was estimated using the income approach and, in particular, developed technology and trademarks/trade names were valued using the relief-from-royalty method and customer relationships and customer backlog were valued using the discounted cash flow method. Royalty rates were estimated using rates applicable to wireless testing equipment and other similar technologies. Based upon this allocation, Teradyne determined that the Wireless Test reporting unit goodwill is valued at $8.0 million and recorded an impairment loss of $254.9 million in the second quarter of 2016. In the fourth quarter of 2017, Teradyne performed the annual goodwill impairment test. Teradyne completed step one of the two-step In the fourth quarter of 2016, Teradyne performed the annual goodwill impairment test. Teradyne completed step one of the two-step In 2015, Teradyne performed step one of the two-step The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2017 and 2016 are as follows: Industrial Automation System Test Wireless Test Semiconductor Test Total (in thousands) Balance at December 31, 2015: Goodwill $ 214,975 $ 158,699 $ 361,819 $ 260,540 $ 996,033 Accumulated impairment losses — (148,183 ) (98,897 ) (260,540 ) (507,620 ) 214,975 10,516 262,922 — 488,413 Foreign currency translation adjustment (10,124 ) — — — (10,124 ) Goodwill impairment losses — — (254,946 ) — (254,946 ) Balance at December 31, 2016: Goodwill 204,851 158,699 361,819 260,540 985,909 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) 204,851 10,516 7,976 — 223,343 Foreign currency translation adjustment 28,668 — — — 28,668 Balance at December 31, 2017: Goodwill 233,519 158,699 361,819 260,540 1,014,577 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) $ 233,519 $ 10,516 $ 7,976 $ — $ 252,011 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. As a result of the Wireless Test segment goodwill impairment review in the second quarter of 2016, Teradyne performed an impairment test of the Wireless Test segment’s intangible and long-lived assets. The impairment test is based on a comparison of the estimated undiscounted cash flows to the carrying value of the asset group. If undiscounted cash flows for the asset group are less than the carrying amount, the asset group is written down to its estimated fair value based on a discounted cash flow analysis. The cash flow estimates used to determine the impairment contain management’s best estimates using appropriate assumptions and projections at that time. The fair value of intangible assets was estimated using the income approach and, in particular, developed technology and trademarks/trade names were valued using the relief-from-royalty method and customer relationships were valued using the discounted cash flow method. Royalty rates were estimated using rates applicable to wireless testing equipment and other similar technologies. As a result of the analysis, Teradyne recorded an $83.3 million impairment charge in the second quarter of 2016 in acquired intangible assets impairment on the statements of operations, resulting in a remaining intangible assets balance of $3.6 million at December 31, 2017, for the Wireless Test segment. There were no events or circumstances indicating that the carrying value of intangible and long-lived assets may not be recoverable in 2017 and 2015. Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (226,190 ) $ 1,618 $ 46,305 Customer relationships 92,741 (83,585 ) 171 9,327 Tradenames and trademarks 50,100 (27,120 ) 416 23,396 Non-compete 320 (260 ) — 60 Total intangible assets $ 414,038 $ (337,155 ) $ 2,205 $ 79,088 December 31, 2016 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (206,376 ) $ (5,093 ) $ 59,408 Customer relationships 92,741 (76,707 ) (538 ) 15,496 Tradenames and trademarks 50,100 (23,435 ) (1,308 ) 25,357 Non-compete 320 (180 ) — 140 Total intangible assets $ 414,038 $ (306,698 ) $ (6,939 ) $ 100,401 Aggregate intangible assets amortization expense for the years ended December 31, 2017, 2016, and 2015 was $30.5 million, $52.6 million, and $69.0 million, respectively. Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2018 $ 29,496 2019 25,533 2020 11,249 2021 3,732 2022 2,927 Thereafter 6,151

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies	K. COMMITMENTS AND CONTINGENCIES Purchase Commitments As of December 31, 2017, Teradyne had entered into non-cancelable Commitments Teradyne leases certain of its office buildings and other facilities under various operating lease arrangements that include renewal options and escalation clauses for adjusting rent payments to reflect changes in price indices. Rental expense for leases with fixed escalation clauses is recognized on a straight line basis over the lease term. Rental expense for the years ended December 31, 2017, 2016, and 2015 was $18.9 million, $18.8 million, and $15.9 million, respectively. The following table reflects Teradyne’s non-cancelable Non-cancelable (in thousands) 2018 $ 17,560 2019 14,355 2020 11,851 2021 9,201 2022 7,331 Beyond 2023 7,425 Total $ 67,723 Legal Claims Teradyne is subject to legal proceedings, claims and investigations that arise in the ordinary course of business such as, but not limited to, patent, employment, commercial and environmental matters. Teradyne believes that it has meritorious defenses against all pending claims and intends to vigorously contest them. While it is not possible to predict or determine the outcomes of any pending claims or to provide possible ranges of losses that may arise, Teradyne believes the potential losses associated with all of these actions are unlikely to have a material adverse effect on its business, financial position or results of operations. Guarantees and Indemnification Obligations Teradyne provides indemnification, to the extent permitted by law, to its officers, directors, employees and agents for liabilities arising from certain events or occurrences while the officer, director, employee, or agent, is or was serving, at Teradyne’s request in such capacity. Teradyne has entered into indemnification agreements with certain of its officers and directors. With respect to acquisitions, Teradyne provides indemnifications to or assumes indemnification obligations for the current and former directors, officers and employees of the acquired companies in accordance with the acquired companies’ by-laws Teradyne enters into agreements in the ordinary course of business with customers, resellers, distributors, integrators and suppliers. Most of these agreements require Teradyne to defend and/or indemnify the other party against intellectual property infringement claims brought by a third party with respect to Teradyne’s products. From time to time, Teradyne also indemnifies customers and business partners for damages, losses and liabilities they may suffer or incur relating to personal injury, personal property damage, product liability, breach of confidentiality obligations and environmental claims relating to the use of Teradyne’s products and services or resulting from the acts or omissions of Teradyne, its employees, authorized agents or subcontractors. On occasion, Teradyne has also provided guarantees to customers regarding the delivery and performance of its products in addition to the warranty described below. As a matter of ordinary business course, Teradyne warrants that its products will substantially perform in accordance with its standard published specifications in effect at the time of delivery. Most warranties have a one-year In addition, and in the ordinary course of business, Teradyne provides minimum purchase guarantees to certain vendors to ensure continuity of supply against the market demand. Although some of these guarantees provide penalties for cancellations and/or modifications to the purchase commitments as the market demand decreases, most of the guarantees do not. Therefore, as the market demand decreases, Teradyne re-evaluates With respect to its agreements covering product, business or entity divestitures and acquisitions, Teradyne provides certain representations, warranties and covenants to purchasers and agrees to indemnify and hold such purchasers harmless against breaches of such representations, warranties and covenants. Many of the indemnification claims have a definite expiration date while some remain in force indefinitely. With respect to its acquisitions, Teradyne may, from time to time, assume the liability for certain events or occurrences that took place prior to the date of acquisition. As a matter of ordinary course of business, Teradyne occasionally guarantees certain indebtedness obligations of its subsidiary companies, limited to the borrowings from financial institutions, purchase commitments to certain vendors, and lease commitments to landlords. Based on historical experience and information known as of December 31, 2017 and 2016, except for product warranty, Teradyne has not recorded any liabilities for these guarantees and obligations because the amount would be immaterial.

Net Income (Loss) per Common Sh

Net Income (Loss) per Common Share	12 Months Ended
	Dec. 31, 2017
Net Income (Loss) per Common Share	L. NET INCOME (LOSS) PER COMMON SHARE The following table sets forth the computation of basic and diluted net income (loss) per common share: 2017 2016 2015 (in thousands, except per share amounts) Net income (loss) for basic and diluted net income per share $ 257,692 $ (43,421 ) $ 206,477 Weighted average common shares-basic 198,069 202,578 211,544 Effect of dilutive potential common shares: Restricted stock units 1,800 — 1,130 Incremental shares from assumed conversion of convertible notes (1) 1,298 — — Stock options 335 — 606 Convertible note hedge warrant shares (2) 112 — — Employee stock purchase rights 27 — 41 Dilutive potential common shares 3,572 — 1,777 Weighted average common shares-diluted 201,641 202,578 213,321 Net income (loss) per common share-basic $ 1.30 $ (0.21 ) $ 0.98 Net income (loss) per common share-diluted $ 1.28 $ (0.21 ) $ 0.97 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.80, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the convertible debt, was divided by the average Teradyne stock price for the period. (2) Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $39.91, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive. The computation of diluted net income per common share for 2017 excludes the effect of the potential exercise of stock options to purchase approximately 0.1 million shares because the effect would have been anti-dilutive. The computation of diluted net loss per common share for 2016 excludes the effect of the potential exercise of all outstanding stock options and restricted stock units because Teradyne had a net loss and inclusion would be anti-dilutive. The computation of diluted net income per common share for 2015 excludes the effect of the potential exercise of stock options to purchase approximately 0.2 million shares because the effect would have been anti-dilutive.

Restructuring and Other

Restructuring and Other	12 Months Ended
	Dec. 31, 2017
Restructuring and Other	M. RESTRUCTURING AND OTHER During the year ended December 31, 2017, Teradyne recorded an expense of $7.8 million for the increase in the fair value of the Universal Robots contingent consideration liability, $3.8 million of severance charges related to headcount reduction of 91 people, of which 75 people were in Semiconductor Test, and 8 people each in Industrial Automation and in Corporate, $1.1 million for an impairment of fixed assets in Semiconductor Test, $1.0 million for a lease impairment of a Wireless Test facility in Sunnyvale, CA, which was terminated in September 2017, and $0.8 million of expenses related to an earthquake in Kumamoto, Japan, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake. During the year ended December 31, 2016, Teradyne recorded an expense of $15.9 million for the increase in the fair value of the contingent consideration liability, of which $15.3 million was related to Universal Robots and $0.6 million was related to AIT, $6.0 million of severance charges related to headcount reductions of 146 people, of which 102 people were in Wireless Test and 44 people were in Semiconductor Test, $4.2 million for an impairment of fixed assets, and $0.9 million for expenses related to an earthquake in Kumamoto, Japan, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake. During the year ended December 31, 2015, Teradyne recorded an expense of $5.3 million for the increase in the fair value of the Universal Robots contingent consideration liability, $1.5 million of severance charges related to headcount reductions of 23 people primarily in System Test and Semiconductor Test, and $1.0 million for acquisition costs related to Universal Robots, partially offset by a $2.9 million gain from fair value adjustments to decrease the acquisition contingent consideration liability, of which $1.6 million was related to ZTEC and $1.3 million was related to AIT. The remaining accrual for severance of $1.4 million is reflected in the accrued employees’ compensation and withholdings on the balance sheet and is expected to be paid by December 2018.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2017
Defined Benefit Pension Plans
Retirement Plans	N. 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. The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2017 2016 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 353,616 $ 60,738 $ 351,117 $ 62,290 Service cost 2,239 818 2,302 761 Interest cost 13,151 852 13,630 1,185 Actuarial loss 12,702 262 6,053 5,621 Benefits paid (18,682 ) (994 ) (19,486 ) (1,385 ) Settlements — (28,560 ) — — Expenses paid — (40 ) — (609 ) Non-U.S. — 6,277 — (7,125 ) End of year 363,026 39,353 353,616 60,738 Change in plan assets: Fair value of plan assets: Beginning of year 307,304 27,571 298,404 28,141 Company contributions 4,462 883 4,489 867 Actual return on plan assets 31,422 737 23,897 5,142 Benefits paid (18,682 ) (994 ) (19,486 ) (1,148 ) Settlements — (28,560 ) — — Expenses paid — (40 ) — (609 ) Non-U.S. — 1,710 — (4,822 ) End of year 324,506 1,307 307,304 27,571 Funded status $ (38,520 ) $ (38,046 ) $ (46,312 ) $ (33,167 ) The following table provides amounts recorded within the account line items of the statements of financial position as of December 31: 2017 2016 United States Foreign United States Foreign (in thousands) Retirement plans assets $ 17,491 $ — $ 7,712 $ — Accrued employees’ compensation and withholdings (2,524 ) (863 ) (2,591 ) (772 ) Retirement plans liabilities (53,487 ) (37,183 ) (51,433 ) (32,395 ) Funded status $ (38,520 ) $ (38,046 ) $ (46,312 ) $ (33,167 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2017 2016 United States Foreign United States Foreign (in thousands) Prior service cost, before tax $ 58 $ — $ 127 $ — Deferred taxes 539 — 514 — Total recognized in other comprehensive income, net of tax $ 597 $ — $ 641 $ — The estimated portion of prior service cost remaining in accumulated other comprehensive income that is expected to be recognized as a component of net periodic pension cost in 2018 is $0.1 million. The accumulated benefit obligation for the United States defined benefit pension plans was $354.3 million and $342.9 million at December 31, 2017 and 2016, respectively. The accumulated benefit obligation for foreign defined benefit pension plans was $34.7 million and $56.6 million at December 31, 2017 and 2016, respectively. Information for pension plans with an accumulated benefit obligation in excess of plan assets as of December 31: 2017 2016 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 56.0 $ 39.4 $ 54.0 $ 34.3 Accumulated benefit obligation 51.6 34.7 48.0 30.1 Fair value of plan assets — 1.3 — 1.1 Expense For the years ended December 31, 2017, 2016, and 2015, Teradyne’s net periodic pension (income) cost was comprised of the following: 2017 2016 2015 United States Foreign United States Foreign United States Foreign (in thousands) Components of Net Periodic Pension (Income) Cost: Service cost $ 2,239 $ 818 $ 2,302 $ 761 $ 2,462 $ 1,006 Interest cost 13,151 852 13,630 1,185 13,142 1,444 Expected return on plan assets (12,008 ) (165 ) (13,830 ) (443 ) (14,517 ) (781 ) Amortization of prior service cost 70 — 96 — 134 — Net actuarial (gain) loss (6,712 ) (310 ) (4,013 ) 815 10,596 8,415 Curtailment — — — — — (634 ) Total net periodic pension (income) cost $ (3,260 ) $ 1,195 $ (1,815 ) $ 2,318 $ 11,817 $ 9,450 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost (70 ) — (96 ) — (134 ) — Total recognized in other comprehensive income (70 ) — (96 ) — (134 ) — Total recognized in net periodic pension (income) cost and other comprehensive income $ (3,330 ) $ 1,195 $ (1,911 ) $ 2,318 $ 11,683 $ 9,450 Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2017 2016 2015 United States Foreign United States Foreign United States Foreign Discount rate 3.9 % 1.8 % 4.0 % 2.3 % 3.7 % 2.6 % Expected return on plan assets 4.0 2.0 4.8 2.0 4.8 2.6 Salary progression rate 2.6 2.7 2.7 3.2 2.9 3.2 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2017 2016 United States Foreign United States Foreign Discount rate 3.4 % 1.8 % 3.9 % 1.8 % Salary progression rate 2.3 2.7 2.6 2.7 In developing the expected return on plan assets assumption, Teradyne evaluates input from its investment manager and pension consultants, including their forecast of asset class return expectations. Teradyne believes that 4.0% was an appropriate rate to use for fiscal 2017 for the U.S. Qualified Pension Plan (“U.S. Plan”). Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans. The discount rate utilized to determine future pension obligations for the U.S. Plan is based on Citigroup Pension Index adjusted for the plan’s expected cash flows and was 3.4% at December 31, 2017, down from 3.9% at December 31, 2016. Plan Assets As of December 31, 2017, the fair value of Teradyne’s pension plans’ assets totaled $325.8 million of which $324.5 million was related to the U.S. Plan and $1.3 million was related to the Taiwan defined benefit pension plan. Substantially all of Teradyne’s pension plans’ assets are held in individual trusts, which were established for the investment of assets of Teradyne’s sponsored retirement plans. The following table provides weighted average pension asset allocation by asset category at December 31, 2017 and 2016: 2017 2016 United States Foreign United States Foreign Fixed income securities 88.1 % — % 88.1 % — % Equity securities 9.9 — 9.9 — Other 2.0 100.0 2.0 100.0 100.0 % 100.0 % 100.0 % 100.0 % The assets of the U.S. Plan are overseen by the Teradyne Fiduciary Committee which is comprised of members of senior management drawn from appropriate diversified levels of the management team. The Fiduciary Committee is responsible for setting the policy that provides the framework for management of the U.S. Plan assets. In accordance with its responsibilities, the Fiduciary Committee meets on a regular basis to review the performance of the U.S. Plan assets and compliance with the investment policy. The policy sets forth an investment structure for managing U.S. Plan assets, including setting the asset allocation ranges, which are expected to provide an appropriate level of overall diversification required to maximize the long-term return on plan assets for a prudent and reasonable level of risk given prevailing market conditions, total investment return over the long term, and preservation of capital, while maintaining sufficient liquidity to pay the benefits of the U.S. Plan. The investment portfolio will not, at any time, have a direct investment in Teradyne stock. It may have indirect investment in Teradyne stock, if one of the funds selected by the investment manager invests in Teradyne stock. In developing the asset allocation ranges, third party asset allocation studies are periodically performed that consider the current and expected positions of the plan assets and funded status. Based on this study and other appropriate information, the Fiduciary Committee establishes asset allocation ranges taking into account acceptable risk targets and associated returns. The investment return objectives are to avoid excessive volatility and produce a rate of return that at least matches the Policy Index identified below. The manager’s investment performance is reviewed at least annually. Results for the total portfolio and for each major category of assets are evaluated in comparison with appropriate market indices and the Policy Index. The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target Allocation U.S. corporate fixed income Bloomberg Barclays U.S. Corporate A or Better Index 76 % Global equity MSCI World Minimum Volatility Index 10 U.S. government fixed income Bloomberg Barclays U.S. Long Government Bond Index 8 High yield fixed income Bloomberg Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1 Teradyne’s U.S. Plan invests primarily in common trust funds. Units held in the common trust funds are valued at the unit price as reported by the investment manager based on the asset value of the underlying investments; underlying investments in equity securities are valued at the last reported sales price, and underlying investments in fixed-income securities are generally valued using methods based upon market transactions for comparable securities. In the fourth quarter of 2015, the Trustees of the U.K. defined benefit pension plan purchased group annuity insurance contracts. In 2017, the U.K. defined benefit pension was terminated and the obligations and assets of the plan were transferred to an insurance company. During the years ended December 31, 2017 and 2016, there were no transfers of pension assets in or out of Level 1, Level 2 or Level 3. The fair value of pension plan assets by asset category and by level at December 31, 2017 and December 31, 2016 were as follows: December 31, 2017 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 260,294 $ — $ 260,294 $ — $ — $ — $ — U.S. government debt securities — 25,709 — 25,709 — — — — Global equity — 32,120 — 32,120 — — — — Group annuity insurance contracts — — 3,166 3,166 — — — — Other — — — — — 1,307 — 1,307 Cash and cash equivalents 3,217 — — 3,217 — — — — Total $ 3,217 $ 318,123 $ 3,166 $ 324,506 $ — $ 1,307 $ — $ 1,307 The pension plan assets identified as Level 3 above are related to group annuity insurance contracts held by the U.S. Plan. The fair value of these assets was calculated using the present value of future pension payments due under the group annuity insurance contracts. December 31, 2016 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 246,528 $ — $ 246,528 $ — $ — $ — $ — U.S. government debt securities — 24,322 — 24,322 — — — — Global equity — 30,360 — 30,360 — — — — Group annuity insurance contracts — — 3,071 3,071 — — 26,385 26,385 Other — — — — — 1,124 — 1,124 Cash and cash equivalents 3,023 — — 3,023 62 — — 62 Total $ 3,023 $ 301,210 $ 3,071 $ 307,304 $ 62 $ 1,124 $ 26,385 $ 27,571 The pension plan assets identified as Level 3 above are related to group annuity insurance contracts held by the U.K. defined benefit pension plan and the U.S. Plan. Changes in the fair value of Level 3 group annuity insurance contracts for the years ended December 31, 2017 and 2016 were as follows: Group Annuity Insurance Contracts (in thousands) Balance at December 31, 2015 $ 29,392 Purchases of group annuity insurance contracts 709 Interest and market value adjustments 5,308 Benefits paid (611 ) Other (634 ) Non-U.S. (4,708 ) Balance at December 31, 2016 29,456 Settlements (28,560 ) Interest and market value adjustments 959 Benefits paid (244 ) Other (61 ) Non-U.S. 1,616 Balance at December 31, 2017 $ 3,166 Contributions Teradyne’s funding policy is to make contributions to the plans in accordance with local laws and to the extent that such contributions are tax deductible. During 2017, Teradyne contributed $1.9 million to the U.S. Plan, $2.6 million to the U.S. supplemental executive defined benefit pension plan and $0.9 million to certain qualified plans for non-U.S. non-U.S. non-U.S. Expected Future Pension Benefit Payments Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2018 $ 19,387 $ 886 2019 19,022 887 2020 19,688 1,253 2021 20,246 1,002 2022 20,994 952 2023-2027 110,214 6,294 Postretirement Benefit Plans In addition to receiving pension benefits, U.S. Teradyne employees who meet early retirement eligibility requirements as of their termination dates may participate in Teradyne’s Welfare Plan, which includes medical and dental benefits up to age 65. Death benefits provide a fixed sum to retirees’ survivors and are available to all retirees. Substantially all of Teradyne’s current U.S. employees could become eligible for these benefits, and the existing benefit obligation relates primarily to those employees. The December 31 balances of the postretirement assets and obligations are shown below: 2017 2016 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 5,510 $ 6,030 Service cost 34 37 Interest cost 201 218 Actuarial loss 398 5 Special termination benefits 591 — Benefits paid (557 ) (687 ) Plan amendments — (93 ) End of year 6,177 5,510 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 557 687 Benefits paid (557 ) (687 ) End of year — — Funded status $ (6,177 ) $ (5,510 ) The following table provides amounts recorded within the account line items of financial position as of December 31: 2017 2016 (in thousands) Accrued employees’ compensation and withholdings $ (591 ) $ (571 ) Retirement plans liability (5,586 ) (4,939 ) Funded status $ (6,177 ) $ (5,510 ) The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2017 2016 (in thousands) Prior service credit, before tax $ (622 ) $ (1,118 ) Deferred taxes (1,472 ) (1,292 ) Total recognized in other comprehensive income, net of tax $ (2,094 ) $ (2,410 ) The estimated portion of prior service credit remaining in accumulated other comprehensive income that is expected to be recognized as a component of net periodic postretirement benefit income in 2018 is $(0.1) million. Expense For the years ended December 31, 2017, 2016, and 2015, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following: 2017 2016 2015 (in thousands) Components of Net Periodic Postretirement Benefit Cost (income): Service cost $ 34 $ 37 $ 48 Interest cost 201 218 237 Amortization of prior service credit (496 ) (607 ) (598 ) Net actuarial loss (gain) 398 5 (648 ) Special termination benefits 591 — — Total net periodic postretirement benefit cost (income) 728 (347 ) (961 ) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service cost — (93 ) — Reversal of amortization items: Prior service credit 496 607 598 Total recognized in other comprehensive income 496 514 598 Total recognized in net periodic postretirement cost (income) and other comprehensive income $ 1,224 $ 167 $ (363 ) Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2017 2016 2015 Discount rate 3.9 % 3.9 % 3.5 % Initial health care cost trend rate 7.3 7.5 7.5 Ultimate health care cost trend rate 5.0 5.0 5.0 Year in which ultimate health care cost trend rate is reached 2023 2023 2022 Weighted Average Assumptions to Determine Postretirement Benefit Obligation as of December 31: 2017 2016 2015 Discount rate 3.4 % 3.9 % 3.9 % Initial medical trend 7.9 7.3 7.5 Ultimate health care trend 4.5 5.0 5.0 Medical cost trend rate decrease to ultimate rate in year 2026 2023 2023 Assumed health care trend rates could have a significant effect on the amounts reported for health care plans. A one percentage point change in the assumed health care cost trend rates for the year ended December 31, 2017 would have the following effects: 1 Percentage Point Increase 1 Percentage Point Decrease (in thousands) Effect on total service and interest cost components $ 3 $ (3 ) Effect on postretirement benefit obligations 64 (60 ) Expected Future Benefit Payments Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2018 $ 591 2019 597 2020 535 2021 502 2022 439 2023-2027 1,665

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Stock-Based Compensation	O. STOCK-BASED COMPENSATION Stock Compensation Plans Under Teradyne’s stock compensation plans, Teradyne grants stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”). Stock options to purchase Teradyne’s common stock at 100% of the fair market value on the grant date vest in equal annual installments over four years from the grant date and have a maximum term of seven years. Time-based restricted stock unit awards granted to employees vest in equal annual installments over four years. Restricted stock unit awards granted to non-employee Commencing in January 2014, Teradyne granted performance-based restricted stock units (“PRSUs”) to its executive officers with a performance metric based on relative total shareholder return (“TSR”). For TSR grants issued in 2015, Teradyne’s three-year TSR performance is measured against the Philadelphia Semiconductor Index. For TSR grants issued in 2017 and 2016, Teradyne’s three-year TSR performance is measured against the New York Stock Exchange (“NYSE”) Composite Index. The final number of TSR PRSUs that vest will vary based upon the level of performance achieved from 200% to 0% of the target shares and is capped at four times the grant date value. The TSR PRSUs will vest upon the three-year anniversary of the grant date. The TSR PRSUs are valued using a Monte Carlo simulation model. The number of units expected to be earned, based upon the achievement of the TSR market condition, is factored into the grant date Monte Carlo valuation. Compensation expense is recognized on a straight-line basis over the three-year service period. Compensation expense is recognized regardless of the eventual number of units that are earned based upon the market condition, provided the executive officer remains an employee at the end of the three-year period. Compensation expense is reversed if at any time during the three-year service period the executive officer is no longer an employee, subject to the retirement and termination eligibility provisions noted below. In January 2017 and 2016, Teradyne granted PRSUs to its executive officers with a performance metric based on three-year cumulative non-GAAP Non-GAAP non-cash non-recurring Beginning with PRSUs granted in January 2014, if the recipient’s employment ends prior to the determination of the performance percentage due to (1) permanent disability or death or (2) retirement or termination other than for cause, after attaining both at least age sixty and at least ten years of service, then all or a portion of the recipient’s PRSUs (based on the actual performance percentage achieved on the determination date) will vest on the date the performance percentage is determined. Except as set forth in the preceding sentence, no PRSUs will vest if the executive officer is no longer an employee at the end of the three-year period. During 2017, 2016, and 2015 Teradyne granted 0.1 million, 0.1 million, and 0.2 million TSR PRSUs, respectively, with a grant date fair value of $35.66, $20.29 and $18.21, respectively. The fair value was estimated using the Monte Carlo simulation model with the following assumptions: 2017 2016 2015 Risk-free interest rate 1.5 % 1.0 % 0.8 % Teradyne volatility-historical 26.6 % 27.0 % 28.2 % NYSE Composite Index volatility-historical 13.4 % 13.1 % — Philadelphia Semiconductor Index volatility-historical — — 19.7 % Dividend yield 1.0 % 1.2 % 1.3 % Expected volatility was based on the historical volatility of Teradyne’s stock and the NYSE Composite Index for the 2017 and 2016 grants and Philadelphia Semiconductor Index for the 2015 grant, over the most recent three-year period. The risk-free interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield for 2017, 2016 and 2015 was based upon an estimated annual dividend amount of $0.28 per share for 2017 and $0.24 per share for 2016 and 2015 divided by Teradyne’s stock price on the grant date of $28.56 for the 2017 grant, $19.43 for the 2016 grant, and $18.10 for the 2015 grant. During 2017 and 2016, Teradyne granted 0.1 million PBIT PRSUs with a grant date fair value of $27.72 and $18.71, respectively. During 2017, 2016, and 2015, Teradyne granted 0.8 million, 1.2 million, and 1.5 million of service-based restricted stock unit awards to employees, respectively, at a weighted average grant date fair value of $28.19, $18.88, and $17.51, respectively. During 2017, 2016, and 2015, Teradyne granted 0.1 million of service-based restricted stock unit awards to non-employee During 2017, 2016, and 2015, Teradyne granted 0.1 million of service-based stock options to executive officers at a weighted average grant date fair value of $7.13, $5.30, and $4.43, respectively. The fair value of the stock options at grant date was estimated using the Black-Scholes option-pricing model with the following assumptions: 2017 2016 2015 Expected life (years) 5.0 5.0 4.0 Risk-free interest rate 2.0 % 1.4 % 1.1 % Volatility-historical 27.8 % 32.9 % 33.4 % Dividend yield 1.0 % 1.2 % 1.3 % Teradyne determined the stock option’s expected life based upon historical exercise data for executive officers, the age of executives and the terms of the stock option award. Volatility was determined using historical volatility for a period equal to the expected life. The interest rate was determined using the U.S. Treasury yield curve in effect at the time of grant. Dividend yield was based upon an estimated annual dividend amount of $0.28 per share for 2017 and $0.24 per share for 2016 and 2015 divided by Teradyne’s stock price on the grant date of $28.56 for the 2017 grants, $19.43 for the 2016 grants, and $18.10 for the 2015 grants. Stock compensation plan activity for the years 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Restricted Stock Units: Non-vested 3,778 4,070 4,352 Awarded 939 1,471 1,681 Vested (1,434 ) (1,530 ) (1,679 ) Forfeited (109 ) (233 ) (284 ) Non-vested 3,174 3,778 4,070 Stock Options: Outstanding at January 1 926 1,121 1,507 Granted 111 130 132 Exercised (501 ) (324 ) (518 ) Forfeited — — — Expired (5 ) (2 ) — Outstanding at December 31 531 926 1,121 Vested and expected to vest at December 31 531 926 1,121 Exercisable at December 31 233 598 779 Total shares available for the years 2017, 2016, and 2015: 2017 2016 2015 (in thousands) Shares available: Available for grant at January 1 9,546 10,914 12,443 Options granted (111 ) (130 ) (132 ) Restricted stock units awarded (939 ) (1,471 ) (1,681 ) Restricted stock units forfeited 109 233 284 Additional shares reserved — — — Available for grant at December 31 8,605 9,546 10,914 Weighted average restricted stock unit award date fair value information for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Non-vested $ 18.27 $ 17.66 $ 17.35 Awarded 28.91 18.95 17.66 Vested 17.90 17.36 16.93 Forfeited 20.35 17.80 17.28 Non-vested $ 21.71 $ 18.27 $ 17.66 Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Vested $ 40,649 $ 30,008 $ 32,200 Outstanding 132,875 95,952 84,129 Expected to vest 130,594 91,871 79,611 Restricted stock units weighted average remaining contractual terms (in years) information at December 31, for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Outstanding 1.00 1.04 1.09 Expected to vest 0.99 1.03 1.08 Weighted average stock options exercise price information for the year ended December 31, 2017 follows: 2017 Outstanding at January 1 $ 11.93 Options granted 28.56 Options exercised 13.60 Options forfeited 3.04 Options cancelled — Outstanding at December 31 13.92 Exercisable at December 31 2.95 The total cash received from employees as a result of employee stock options exercises during the years ended December 31, 2017, 2016, and 2015, was $6.8 million, $2.9 million and $2.8 million, respectively. In connection with these exercises, the tax benefit realized by Teradyne for the years ended December 31, 2017, 2016, and 2015, was $2.5 million, $0.8 million and $2.1 million, respectively. Stock option aggregate intrinsic value information for the years ended December 31, 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Exercised $ 8,035 $ 3,729 $ 7,255 Outstanding 14,831 12,468 11,729 Vested and expected to vest 14,831 12,468 11,729 Exercisable 9,076 10,217 10,716 Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Outstanding 4.1 3.9 4.2 Vested and expected to vest 4.1 3.9 4.2 Exercisable 2.8 3.2 3.9 Significant option groups outstanding at December 31, 2017 and related weighted average price and remaining contractual life information follow: Options Outstanding Options Exercisable Range Of Exercise Prices Weighted- Average Remaining Contractual Life (Years) Shares Weighted- Average Exercise Price Shares Weighted- Average Exercise Price (shares in thousands) $1.48 – $2.58 2.19 99 $ 1.81 99 $ 1.81 $2.67 – $7.71 3.17 126 2.89 126 2.89 $18.10 – $19.43 4.48 194 18.91 8 18.51 $28.56 6.08 112 28.56 — — 531 $ 13.92 233 $ 2.95 As of December 31, 2017, total unrecognized expense related to non-vested Employee Stock Purchase Plan Under the Teradyne 1996 Employee Stock Purchase Plan (“ESPP”), eligible employees may purchase shares of common stock through regular payroll deductions of up to 10% of their compensation, to a maximum of shares with a fair market value of $25,000 per calendar year, not to exceed 6,000 shares. Under the plan, the price paid for the common stock is equal to 85% of the stock price on the last business day of the six-month In July 2017, 0.3 million shares of common stock were issued to employees who participated in the plan during the first half of 2017 at the price of $25.53 per share. In January 2018, Teradyne issued 0.3 million shares of common stock to employees who participated in the plan during the second half of 2017 at the price of $35.59 per share. In July 2016, 0.5 million shares of common stock were issued to employees who participated in the plan during the first half of 2016 at the price of $16.74 per share. In January 2017, Teradyne issued 0.4 million shares of common stock to employees who participated in the plan during the second half of 2016 at the price of $21.59 per share. In July 2015, 0.5 million shares of common stock were issued to employees who participated in the plan during the first half of 2015 at the price of $16.40 per share. In January 2016, Teradyne issued 0.5 million shares of common stock to employees who participated in the plan during the second half of 2015 at the price of $17.57 per share. As of December 31, 2017, there were 3.1 million shares available for grant under the ESPP. The effect to income from operations for recording stock-based compensation for the years ended December 31 was as follows: 2017 2016 2015 (in thousands) Cost of revenues $ 3,212 $ 3,153 $ 3,065 Engineering and development 9,370 9,458 9,362 Selling and administrative 21,515 18,139 18,024 Stock-based compensation 34,097 30,750 30,451 Income tax benefit (10,462 ) (8,752 ) (8,528 ) Total stock-based compensation expense after income taxes $ 23,635 $ 21,998 $ 21,923

Savings Plan

Savings Plan	12 Months Ended
	Dec. 31, 2017
Savings Plan	P. SAVINGS PLAN Teradyne sponsors a defined contribution employee retirement savings plan (“Savings Plan”) covering substantially all U.S. employees. Under the Savings Plan, employees may contribute up to 20% of their compensation (subject to Internal Revenue Service limitations). The Savings Plan provides for a discretionary employer match that is determined each year. In 2017, 2016 and 2015, Teradyne matched 100% of eligible employee contributions up to 4% of their compensation for employees not accruing benefits in the U.S. Qualified Pension Plan. There was no match for employees still actively accruing benefits in the U.S. Qualified Pension Plan. Teradyne’s contributions vest 25% per year for the first four years of employment, and contributions for those employees with four years of service vest immediately. In addition, Teradyne established an unfunded U.S. Supplemental Savings Plan to provide savings benefits in excess of those allowed by Employee Retirement Income Security Act of 1974 and the Internal Revenue Code. The provisions of this plan are the same as the Savings Plan. Teradyne also established defined contribution savings plans for its foreign employees. Under Teradyne’s savings plans, amounts charged to the statements of operations for the years ended December 31, 2017, 2016, and 2015 were $15.3 million, $14.5 million, and $13.5 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes	Q. INCOME TAXES The components of income (loss) before income taxes and the provision (benefit) for income taxes as shown in the consolidated statements of operations were as follows: 2017 2016 2015 (in thousands) Income (loss) before income taxes: U.S. $ 76,699 $ (341,018 ) $ 56,270 Non-U.S. 447,713 285,958 196,854 $ 524,412 $ (55,060 ) $ 253,124 Provision (benefit) for income taxes: Current: U.S. Federal $ 162,679 $ 7,750 $ 16,635 Non-U.S. 64,313 41,579 35,707 State 2,623 1,968 1,429 229,615 51,297 53,771 Deferred: U.S. Federal 43,687 (51,482 ) (574 ) Non-U.S. (6,476 ) (9,240 ) (7,761 ) State (106 ) (2,214 ) 1,211 37,105 (62,936 ) (7,124 ) Total provision (benefit) for income taxes: $ 266,720 $ (11,639 ) $ 46,647 Income tax expense for 2017 totaled $266.7 million. Income tax benefit for 2016 totaled $11.6 million. Income tax expense for 2015 totaled $46.6 million. The effective tax rate for 2017, 2016, and 2015 was 50.9%, 21.1%, and 18.4% respectively. On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act of 2017 (the “Tax Reform Act”), making significant changes to the Internal Revenue Code. Among other changes, the Tax Reform Act permanently reduces the corporate tax rate from 35% to 21% effective for tax years beginning after December 31, 2017, shifts the U.S. tax regime from a worldwide system to a modified territorial tax system and requires companies to pay a transition tax on earnings of certain foreign subsidiaries that were previously tax deferred. The Tax Reform Act has significant direct and indirect implications for accounting for income taxes under ASC 740 “Accounting for Income Taxes” “Income Tax Accounting Implications of the Tax Cuts and Jobs Act” one-time In addition to the introduction of a modified territorial tax system, the Tax Reform Act includes two new U.S. tax base erosion provisions, the global intangible low-taxed The BEAT provisions in the Tax Reform Act eliminate the deduction of certain base-erosion payments made to related foreign corporations, and impose a minimum tax if greater than regular tax. This provision is not effective for Teradyne until the 2018 calendar year. Teradyne does not presently expect that it will be subject to this tax. The increase in the effective tax rate from 2016 to 2017 is primarily attributable to the effect of changes in U.S Federal tax law which resulted in one-time non-deductible non-taxable The increase in the effective tax rate from 2015 to 2016 resulted from a shift in the geographic distribution of income which decreased income subject to taxation in the U.S. relative to lower tax rate jurisdictions, reductions in uncertain tax positions resulting from the expiration of statutes and the settlement of an audit, and an increase in non-taxable non-deductible A reconciliation of the effective tax rate for the years 2017, 2016, and 2015 is as follows: 2017 2016 2015 U.S. statutory federal tax rate 35.0 % 35.0 % 35.0 % U.S. transition tax 28.7 — — Impact of rate change on deferred tax 6.4 — — Uncertain tax positions 1.7 (2.6 ) 2.2 Foreign taxes (16.3 ) 78.0 (13.8 ) Foreign tax credits (2.2 ) 49.1 (2.7 ) U.S. research and development credit (1.6 ) 15.8 (3.0 ) Equity compensation (0.8 ) (2.7 ) 0.6 Domestic production activities deduction (0.3 ) 2.3 (1.0 ) State income taxes, net of federal tax benefit — 2.3 0.4 Goodwill impairment — (162.1 ) — U.S. alternative minimum tax credit — 3.7 — Inventory cost capitalization — 1.8 — Other, net 0.3 0.5 0.7 50.9 % 21.1 % 18.4 % Teradyne qualifies for a tax holiday in Singapore by fulfilling the requirements of an agreement with the Singapore Economic Development Board under which certain headcount and spending requirements must be met. The tax savings attributable to the tax holiday for the years ended December 31, 2017, 2016, and 2015 were $24.8 million or $0.12 per diluted share, $17.0 million or $0.08 per diluted share, and $11.5 million or $0.05 per diluted share, respectively. The tax holiday is scheduled to expire on December 31, 2020. Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2017 and 2016 were as follows: 2017 2016 (in thousands) Deferred tax assets: Tax credits $ 76,083 $ 57,313 Accruals 27,508 27,247 Pension liabilities 22,602 31,581 Inventory valuations 17,793 31,227 Deferred revenue 9,016 12,806 Equity compensation 6,861 9,922 Net operating loss carryforwards 5,440 5,244 Vacation accrual 4,747 7,874 Other 713 630 Gross deferred tax assets 170,763 183,844 Less: valuation allowance (63,919 ) (48,369 ) Total deferred tax assets $ 106,844 $ 135,475 Deferred tax liabilities: Intangible assets $ (16,120 ) $ (22,887 ) Depreciation (12,293 ) (17,117 ) Marketable securities (1,125 ) (210 ) Total deferred tax liabilities $ (29,538 ) $ (40,214 ) Net deferred assets $ 77,306 $ 95,261 During 2017, Teradyne’s valuation allowance increased by $15.6 million, of which $11.3 million resulted from the effect of the reduction in the U.S. Federal corporate tax rate on the valuation allowance associated with state credits and net operating losses. The remaining change is primarily due to an increase in the deferred tax assets related to state tax credits generated in 2017. As of December 31, 2017 and 2016, Teradyne evaluated the likelihood that it would realize the deferred income taxes to offset future taxable income and concluded that it is more likely than not that a substantial majority of its deferred tax assets will be realized through consideration of both the positive and negative evidence. At December 31, 2017 and 2016, Teradyne maintained a valuation allowance for certain deferred tax assets of $63.9 million and $48.4 million, respectively, primarily related to state net operating losses and state tax credit carryforwards, due to the uncertainty regarding their realization. Adjustments could be required in the future if Teradyne estimates that the amount of deferred tax assets to be realized is more or less than the net amount recorded. At December 31, 2017, Teradyne had operating loss carryforwards that expire in the following years: U.S. Federal Operating Loss Carryforwards State Operating Loss Carryforwards Foreign Operating Loss Carryforwards (in thousands) 2018 $ — $ 9,943 $ — 2019 — 174 — 2020 — 130 — 2021 — 2,919 — 2022 — 6,362 — 2023-2027 — 12,296 — 2028-2032 — 34,963 — Beyond 2032 — 4,516 130 Non-expiring — — 7,012 Total $ — $ 71,303 $ 7,142 Teradyne has approximately $123.5 million of tax credit carryforwards including federal business tax credits of approximately $28.3 million which expire in the years 2018 through 2037, alternative minimum tax credits of approximately $6.6 million which do not expire, and state tax credits of $88.6 million, of which $51.4 million do not expire and the remainder expires in the years 2018 through 2037. Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2017, 2016 and 2015 were as follows: 2017 2016 2015 (in thousands) Beginning balance, as of January 1 $ 38,958 $ 36,792 $ 30,418 Additions: Tax positions for current year 8,208 9,766 6,626 Tax positions for prior years 199 187 792 Reductions: Tax positions for prior years (10,573 ) (1,960 ) (708 ) Expiration of statutes (325 ) (3,532 ) — Settlements with tax authorities (204 ) (2,295 ) (336 ) Ending balance as of December 31 $ 36,263 $ 38,958 $ 36,792 Current year and prior year additions include assessment of potential transfer pricing issues worldwide, federal and state tax credits and incentives, capitalization rules, and domestic production activities deductions. Reductions for tax positions for prior years primarily relates to the transition tax charge recorded in the fourth quarter of 2017. Of the $36.3 million of unrecognized tax benefits as of December 31, 2017, $24.8 million would impact the consolidated income tax rate if ultimately recognized. The remaining $11.5 million would impact deferred taxes if recognized. Given the potential outcome of the current examination as well as the impact of the current examination on the potential expiration of the statute of limitations, it is reasonably possible that the balance of unrecognized tax benefits could significantly change within the next twelve months. However, an estimate of the range of reasonably possible adjustments cannot presently be made. Teradyne records all interest and penalties related to income taxes as a component of income tax expense. Accrued interest and penalties related to income tax items at December 31, 2017 and 2016 amounted to $0.3 million and $0.4 million, respectively. For the years ended December 31, 2017, 2016, and 2015, benefit of $0.1 million, $0.1 million, and $0.2 million, respectively, was recorded for interest and penalties related to income tax items. Teradyne is subject to U.S. federal income tax, as well as income tax in multiple state, local and foreign jurisdictions. As of December 31, 2017, all material state and local income tax matters have been concluded through 2012, all material federal income tax matters have been concluded through 2013 and all material foreign income tax matters have been concluded through 2011. However, in some jurisdictions, including the United States, operating losses and tax credits may be subject to adjustment until such time as they are utilized and the year of utilization is closed to adjustment. As of December 31, 2017, Teradyne expects to remit the earnings of non-U.S. non-U.S. non-U.S.

Operating Segment, Geographic a

Operating Segment, Geographic and Significant Customer Information	12 Months Ended
	Dec. 31, 2017
Operating Segment, Geographic and Significant Customer Information	R. OPERATING SEGMENT, GEOGRAPHIC AND SIGNIFICANT CUSTOMER INFORMATION Teradyne has four operating segments (Semiconductor Test, System Test, Industrial Automation, and Wireless Test), which are its reportable segments. The Semiconductor Test segment includes operations related to the design, manufacturing and marketing of semiconductor test products and services. The System Test segment includes operations related to the design, manufacturing and marketing of products and services for defense/aerospace instrumentation test, storage test and circuit-board test. The Industrial Automation segment includes operations related to the design, manufacturing and marketing of collaborative robots. 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 using several factors, of which the primary financial measure is business segment income (loss) from operations before taxes. The accounting policies of the business segments are the same as those described in Note B: “Accounting Policies.” Segment information for the years ended December 31, 2017, 2016, and 2015 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate And Eliminations Consolidated (in thousands) 2017 Revenues $ 1,662,549 $ 192,135 $ 170,056 $ 111,866 $ — $ 2,136,606 Income (loss) before taxes (1)(2) 491,361 10,306 8,763 17,350 (3,368 ) 524,412 Total assets (3) 597,480 97,018 368,037 59,912 1,987,098 3,109,545 Property additions 87,920 5,976 7,044 4,435 — 105,375 Depreciation and amortization expense 58,901 6,646 25,711 5,392 11,425 108,075 2016 Revenues $ 1,368,169 $ 189,846 $ 99,031 $ 96,204 $ — $ 1,753,250 Income (loss) before taxes (1)(2) 311,939 28,916 (16,783 ) (371,409 ) (7,723 ) (55,060 ) Total assets (3) 557,546 110,361 317,635 62,366 1,714,585 2,762,493 Property additions 70,543 3,788 6,755 4,186 — 85,272 Depreciation and amortization expense 58,087 6,551 26,869 25,921 2,581 120,009 2015 Revenues $ 1,201,530 $ 211,584 $ 41,892 $ 184,572 $ — $ 1,639,578 Income (loss) before taxes (1)(2) 260,154 25,101 (7,574 ) (13,830 ) (10,727 ) 253,124 Total assets (3) 610,869 102,547 344,260 427,880 1,063,118 2,548,674 Property additions 79,052 6,228 1,465 3,133 — 89,878 Depreciation and amortization expense 64,415 4,391 14,500 53,440 4,027 140,773 (1) Included in Corporate and Eliminations are: contingent consideration adjustments, pension and postretirement plans actuarial gains (losses), severance charges, impairment of fixed assets and expenses related to the Japan earthquake, property insurance recovery, interest income, interest expense, net foreign exchange gains (losses), and gain from the sale of an equity investment. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges, goodwill impairment charges and an acquired intangible assets impairment charge. (3) Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets. Included in the Semiconductor Test segment are charges in the following accounts: For the Year Ended 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 4,606 $ 9,656 $ 10,508 Restructuring and other—employee severance 1,779 2,860 499 Restructuring and other—impairment of fixed assets 1,124 — — Included in the System Test segment are charges and credits in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 1,918 $ 630 $ 8,324 Restructuring and other—employee severance — (49 ) 1,037 Included in the Industrial Automation segment are charges in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Restructuring and other—employee severance $ 1,414 $ 585 $ — Cost of revenues—inventory step-up — — 1,567 (1) Included in the cost of revenues for the year ended December 31, 2015 is the cost for purchase accounting inventory step-up. Included in the Wireless Test segment are charges in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 2,190 $ 7,207 $ 2,500 Restructuring and other—lease impairment 973 — — Restructuring and other—employee severance — 2,650 — Goodwill impairment charge — 254,946 — Intangible assets impairment charge — 83,339 — Included in the Corporate and Eliminations segment are charges and credits in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ 7,820 $ 15,346 $ 5,339 Restructuring and other—impairment of fixed assets and expenses related to Japan earthquake 755 5,051 — Restructuring and other—employee severance 530 — — Restructuring and other—property insurance recovery (5,064 ) (5,051 ) — Cost of revenues—pension actuarial (gains) losses (2,752 ) (1,025 ) 8,271 Engineering and development—pension actuarial (gains) losses (2,456 ) (1,234 ) 4,658 Selling and administrative—pension actuarial (gains) losses (1,416 ) (944 ) 4,826 Restructuring and other—ZTEC contingent consideration adjustment — — (1,600 ) Restructuring and other—AIT contingent consideration adjustment — 550 (1,250 ) Restructuring and other—acquisition costs — — 1,104 Other (income) expense, net—gain from the sale of an equity investment — — (5,406 ) Information as to Teradyne’s revenues by country is as follows: 2017 2016 2015 (in thousands) Revenues from customers (1): Taiwan $ 687,031 $ 653,076 $ 436,389 China 260,451 174,876 264,898 United States 252,516 221,948 217,386 Korea 206,819 147,882 120,224 Japan 169,093 135,978 128,228 Europe 163,715 117,671 111,903 Malaysia 124,048 103,472 76,707 Philippines 105,850 54,705 96,103 Singapore 101,085 73,172 105,216 Thailand 29,566 43,097 59,104 Rest of the World 36,432 27,373 23,420 $ 2,136,606 $ 1,753,250 $ 1,639,578 (1) Revenues attributable to a country are based on location of customer site. In 2017 and 2016, one customer of Teradyne’s Semiconductor Test segment accounted for 13% and 12 %, respectively, of total consolidated revenues. In 2016 and 2015, a different customer of Teradyne’s Semiconductor Test segment accounted for 12% and 13%, respectively, of total consolidated revenues. Teradyne estimates product demand driven by a single OEM customer, combining direct sales to that customer with sales to the customer’s outsourced semiconductor assembly and test providers (“OSATs”), accounted for approximately 22%, 26%, and 23% of Teradyne’s consolidated revenues in 2017, 2016, and 2015, respectively. Long-lived assets by geographic area: United States Foreign(1) Total (in thousands) December 31, 2017 $ 198,855 $ 69,592 $ 268,447 December 31, 2016 $ 189,195 $ 64,626 $ 253,821 (1) As of December 31, 2017 and 2016, long-lived assets attributable to Singapore were $23.6 million and $31.5 million, respectively.

Stock Repurchase Program

Stock Repurchase Program	12 Months Ended
	Dec. 31, 2017
Stock Repurchase Program	S. STOCK REPURCHASE PROGRAM In January 2015, Teradyne’s Board of Directors cancelled the November 2010 stock repurchase program and authorized a new stock repurchase program for up to $500 million of common stock. In 2015, Teradyne repurchased 15.6 million shares of common stock at an average price of $19.20, for a total cost of $300 million. In 2016, Teradyne repurchased 6.8 million shares of common stock at an average price of $21.39, for a total cost of $146 million. The cumulative repurchases as of December 31, 2016 totaled 22.5 million shares of common stock for $446 million at an average price per share of $19.87. In December 2016, Teradyne’s Board of Directors cancelled the January 2015 stock repurchase program and approved a new $500 million share repurchase authorization which commenced on January 1, 2017. The cumulative repurchases as of December 31, 2017 totaled 5.8 million shares of common stock for $200 million at an average price per share of $34.30.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events	T. SUBSEQUENT EVENTS In January 2018, Teradyne’s Board of Directors declared a quarterly cash dividend of $0.09 per share to be paid on March 23, 2018 to shareholders of record as of February 23, 2018. In January 2018, Teradyne’s Board of Directors cancelled the December 2016 stock repurchase program and authorized a new repurchase program for up to $1.5 billion of common stock through open market purchases or private transactions. Teradyne intends to repurchase $750 million in 2018. While Teradyne declared a quarterly cash dividend and authorized a share repurchase program, it may reduce or eliminate the cash dividend or share repurchase program in the future. Future cash dividends and stock repurchases are subject to the discretion of Teradyne’s Board of Directors which will consider, among other things, Teradyne’s earnings, capital requirements and financial condition.

Supplementary Information

Supplementary Information	12 Months Ended
	Dec. 31, 2017
Supplementary Information	SUPPLEMENTARY INFORMATION (Unaudited) The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2017 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2)(5) (3) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 373,204 $ 610,356 $ 412,854 $ 388,282 Services 83,709 86,545 90,524 91,133 Total revenues 456,913 696,901 503,378 479,415 Cost of revenues: Cost of products 154,966 267,171 169,744 166,667 Cost of services 37,014 38,511 38,848 39,813 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 191,980 305,682 208,592 206,480 Gross profit 264,933 391,219 294,786 272,935 Operating expenses: Selling and administrative 84,906 89,131 86,244 88,006 Engineering and development 76,182 81,728 77,190 70,564 Acquired intangible assets amortization 7,952 8,166 7,028 7,384 Restructuring and other 2,511 2,288 (4,407 ) 8,970 Total operating expenses 171,551 181,313 166,055 174,924 Income from operations 93,382 209,906 128,731 98,011 Non-operating Interest income (3,520 ) (3,292 ) (4,517 ) (6,476 ) Interest expense 5,402 5,509 5,372 5,380 Other (income) expense, net (516 ) 812 439 1,023 Income before income taxes 92,016 206,877 127,437 98,084 Income tax provision 6,795 31,901 24,017 204,007 Net income (loss) $ 85,221 $ 174,976 $ 103,420 $ (105,923 ) Net income (loss) per common share—basic $ 0.43 $ 0.88 $ 0.52 $ (0.54 ) Net income (loss) per common share—diluted $ 0.42 $ 0.87 $ 0.52 $ (0.54 ) Cash dividend declared per common share $ 0.07 $ 0.07 $ 0.07 $ 0.07 (1) Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges. (2) Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges. (3) Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges. (4) Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets. (5) Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. 2016 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1)(5) (2)(5) (3)(5) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 358,139 $ 456,832 $ 334,610 $ 303,667 Services 72,855 74,960 75,865 76,322 Total revenues 430,994 531,792 410,475 379,989 Cost of revenues: Cost of products 167,555 215,795 148,266 127,481 Cost of services 33,107 33,127 34,850 33,502 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 200,662 248,922 183,116 160,983 Gross profit 230,332 282,870 227,359 219,006 Operating expenses: Selling and administrative 79,174 81,425 78,794 76,289 Engineering and development 73,464 76,109 71,400 70,052 Acquired intangible assets amortization 19,994 16,244 8,487 7,923 Acquired intangible assets impairment — 83,339 — — Goodwill impairment — 254,946 — — Restructuring and other 1,587 2,608 12,177 5,570 Total operating expenses 174,219 514,671 170,858 159,834 Income (loss) from operations 56,113 (231,801 ) 56,501 59,172 Non-operating Interest income (1,642 ) (1,666 ) (2,892 ) (3,095 ) Interest expense 710 691 633 1,604 Other (income) expense, net (147 ) (9 ) (921 ) 1,779 Income (loss) before income taxes 57,192 (230,817 ) 59,681 58,884 Income tax provision (benefit) 7,206 (7,271 ) (4,113 ) (7,461 ) Net income (loss) $ 49,986 $ (223,546 ) $ 63,794 $ 66,345 Net income (loss) per common share—basic $ 0.24 $ (1.10 ) $ 0.32 $ 0.33 Net income (loss) per common share—diluted $ 0.24 $ (1.10 ) $ 0.31 $ 0.33 Cash dividend declared per common share $ 0.06 $ 0.06 $ 0.06 $ 0.06 (1) Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (2) Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake. (3) Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (4) Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (5) Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts	TERADYNE, INC. SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Accounts receivable: 2017 Allowance for doubtful accounts $ 2,356 $ 4 $ — $ 141 $ 2,219 2016 Allowance for doubtful accounts $ 2,407 $ — $ — $ 51 $ 2,356 2015 Allowance for doubtful accounts $ 2,491 $ — $ — $ 84 $ 2,407 Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Inventory: 2017 Inventory reserve $ 116,016 $ 8,844 $ (126 ) $ 21,838 $ 102,896 2016 Inventory reserve $ 119,376 $ 17,493 $ 4,417 $ 25,270 $ 116,016 2015 Inventory reserve $ 111,252 $ 21,332 $ 1,680 $ 14,888 $ 119,376 Column A Column B Column C Column D Column E Column F Description Balance at Beginning of Period Additions Charged to Cost and Expenses Other Deductions Balance at End of Period (in thousands) Valuation reserve deducted in the balance sheet from the asset to which it applies: Deferred taxes: 2017 Valuation allowance $ 48,369 $ 15,571 $ — $ 21 $ 63,919 2016 Valuation allowance $ 43,039 $ 5,413 $ — $ 83 $ 48,369 2015 Valuation allowance $ 41,737 $ 1,322 $ — $ 20 $ 43,039

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Preparation of Financial Statements and Use of Estimates	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. On an on-going
Revenue Recognition	Revenue Recognition Teradyne recognizes revenues, including revenues from distributors, when there is persuasive evidence of an arrangement, title and risk of loss have passed, delivery has occurred or the services have been rendered, the sales price is fixed or determinable and collection of the related receivable is reasonably assured. Title and risk of loss generally pass to Teradyne’s customers upon shipment or at delivery destination point. In circumstances where either title or risk of loss pass upon destination, acceptance or cash payment, Teradyne defers revenue recognition until such events occur except when title transfer is tied to cash payment outside the United States. Outside the United States, Teradyne recognizes revenue upon shipment or at delivery destination point, even if Teradyne retains a form of title to products delivered to customers, provided the sole purpose is to enable Teradyne to recover the products in the event of customer payment default and the arrangement does not prohibit the customer’s use or resale of the product in the ordinary course of business. Teradyne’s equipment has non-software For multiple element arrangements, Teradyne allocates revenue to all deliverables based on their relative selling prices. In such circumstances, a hierarchy is used to determine the selling price for allocating revenue to deliverables as follows: (i) vendor-specific objective evidence of selling price (“VSOE”), (ii) third-party evidence of selling price (“TPE”), and (iii) best estimate of the selling price (“BESP”). For a delivered item to be considered a separate unit the delivered item must have value to the customer on a standalone basis and the delivery or performance of the undelivered item must be considered probable and substantially in Teradyne’s control. Teradyne’s post-shipment obligations include installation, training services, one-year 605-20, Separately Priced Extended Warranty and Product Maintenance Contracts 605-25, Revenue Recognition Multiple-Element Arrangements. Teradyne’s products are generally subject to warranty and related costs of the warranty are provided for in cost of revenues when product revenue is recognized. Teradyne classifies shipping and handling costs in cost of revenue. Teradyne does not provide its customers with contractual rights of return for any of its products. As of December 31, 2017 and 2016, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2017 2016 (in thousands) Maintenance and training $ 57,256 $ 46,803 Customer advances, undelivered elements and other 32,047 32,938 Extended warranty 24,438 28,200 Total deferred revenue and customer advances $ 113,741 $ 107,941
Product Warranty	Product Warranty Teradyne generally provides a one-year Amount (in thousands) Balance at December 31, 2014 $ 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 6,925 Accruals for warranties issued during the period 14,291 Accruals related to pre-existing (1,354 ) Settlements made during the period (12,659 ) Balance at December 31, 2016 7,203 Accruals for warranties issued during the period 14,223 Accruals related to pre-existing (379 ) Settlements made during the period (12,847 ) Balance at December 31, 2017 $ 8,200 When Teradyne receives revenue for extended warranties, beyond one year, it is deferred and recognized on a straight-line basis over the contract period. Related costs are expensed as incurred. The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2014 $ 34,197 Acquisition 870 Deferral of new extended warranty revenue 17,698 Recognition of extended warranty deferred revenue (22,741 ) Balance at December 31, 2015 30,024 Deferral of new extended warranty revenue 19,909 Recognition of extended warranty deferred revenue (21,733 ) Balance at December 31, 2016 28,200 Deferral of new extended warranty revenue 20,513 Recognition of extended warranty deferred revenue (24,275 ) Balance at December 31, 2017 $ 24,438
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The volatility of the industries that Teradyne serves can cause certain of its customers to experience shortages of cash flows, which can impact their ability to make required payments. Teradyne maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Estimated allowances for doubtful accounts are reviewed periodically taking into account the customer’s recent payment history, the customer’s current financial statements and other information regarding the customer’s credit worthiness. Account balances are written off against the allowance when it is determined the receivable will not be recovered.
Inventories	Inventories Inventories are stated at the lower of cost (first-in, first-out
Investments	Investments Teradyne accounts for its investments in debt and equity securities in accordance with the provisions of ASC 320-10, Investments—Debt and Equity Securities 320-10 available-for-sale held-to-maturity • The length of time and the extent to which the market value has been less than cost; • The financial condition and near-term prospects of the issuer; and • The intent and ability to retain the investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. As defined in ASC 820-10, Fair Value Measurements and Disclosures, ASC 820-10 Level 1: Quoted prices in active markets for identical assets as of the reporting date. Level 2: Inputs other than Level 1, that are observable either directly or indirectly as of the reporting date. For example, a common approach for valuing fixed income securities is the use of matrix pricing. Matrix pricing is a mathematical technique used to value securities by relying on the securities’ relationship to other benchmark quoted prices, and therefore is considered a Level 2 input. Level 3: Unobservable inputs that are not supported by market data. Unobservable inputs are developed based on the best information available, which might include Teradyne’s own data. In accordance with ASC 820-10,
Prepayments	Prepayments Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2017 2016 (in thousands) Contract manufacturer and supplier prepayments $ 82,503 $ 84,473 Prepaid maintenance and other services 8,189 7,676 Prepaid taxes 5,039 4,664 Other prepayments 12,386 11,641 Total prepayments $ 108,117 $ 108,454
Retirement and Postretirement Plans	Retirement and Postretirement Plans Teradyne recognizes net actuarial gains and losses and the change in the fair value of the plan assets in its operating results in the year in which they occur or upon any interim remeasurement of the plans. Teradyne calculates the expected return on plan assets using the fair value of the plan assets. Actuarial gains and losses are generally measured annually as of December 31 and, accordingly, recorded during the fourth quarter of each year or upon any interim remeasurement of the plans.
Goodwill, Intangible and Long-Lived Assets	Goodwill, Intangible and Long-Lived Assets Teradyne accounts for goodwill and intangible assets in accordance with ASC 350-10, Intangibles-Goodwill and Other. 350-10, more-likely-than-not two-step more-likely-than-not two-step In accordance with ASC 360-10, Impairment or Disposal of Long-Lived Assets,
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost and depreciated over the estimated useful lives of the assets. Leasehold improvements and major renewals are capitalized and included in property, plant and equipment accounts while expenditures for maintenance and repairs and minor renewals are charged to expense. When assets are retired, the assets and related accumulated depreciation are removed from the accounts and any resulting gain or loss is reflected in the consolidated statements of operations. Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years Test systems manufactured internally are used by Teradyne for customer evaluations and manufacturing and support of its customers. Teradyne depreciates the test systems manufactured internally over a six-year
Engineering and Development Costs	Engineering and Development Costs Teradyne’s products are highly technical in nature and require a large and continuing engineering and development effort. Software development costs incurred prior to the establishment of technological feasibility are charged to expense. Software development costs incurred subsequent to the establishment of technological feasibility are capitalized until the product is available for release to customers. To date, the period between achieving technological feasibility and general availability of the product has been short and software development costs eligible for capitalization have not been material. Engineering and development costs are expensed as incurred and consist primarily of salaries, contractor fees including non-recurring
Stock Compensation Plans and Employee Stock Purchase Plan	Stock Compensation Plans and Employee Stock Purchase Plan Stock-based compensation expense is based on the grant-date fair value estimated in accordance with the provisions of ASC 718-10, Compensation-Stock Compensation In March 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-09, “Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting.” Adoption of this ASU required recognition of a cumulative effect adjustment to retained earnings for any prior year excess tax benefits or tax deficiencies not previously recorded. The cumulative effect adjustment of $39 million was recorded in the first quarter of 2017 as an increase to retained earnings and deferred tax assets. This ASU also required a change in how Teradyne recognizes the excess tax benefits or tax deficiencies related to stock-based compensation. Prior to adopting ASU 2016-09, paid-in 2016-09, ASU 2016-09 In addition, under ASU 2016-09, Upon adoption of ASU 2016-09, Under its stock compensation plans, Teradyne has granted stock options, restricted stock units and performance-based restricted stock units, and employees are eligible to purchase Teradyne’s common stock through its Employee Stock Purchase Plan (“ESPP”).
Income Taxes	Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The measurement of deferred tax assets is reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be realized. Teradyne performed the required assessment of positive and negative evidence regarding the realization of the net deferred tax assets in accordance with ASC 740, “Accounting for Income Taxes.” tax-planning
Advertising Costs	Advertising Costs Teradyne expenses all advertising costs as incurred. Advertising costs were $9.1 million, $6.4 million, and $3.3 million in 2017, 2016, and 2015, respectively.
Translation of Non-U.S. Currencies	Translation of Non-U.S. The functional currency for all subsidiaries is the U.S. dollar, except for the Industrial Automation segment for which the local currency is its functional currency. All foreign currency denominated monetary assets and liabilities are remeasured on a monthly basis into the functional currency using exchange rates in effect at the end of the period. All foreign currency denominated non-monetary Net foreign exchange gains and losses resulting from remeasurement are included in other (income) expense, net. For the years ended December 31, 2017, 2016, and 2015, losses (gains) from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $2.9 million, $(8.0) million, and $(2.5) million, respectively. These amounts do not reflect the corresponding (gains) losses from foreign exchange contracts. See Note G: “Financial Instruments” regarding foreign exchange contracts.
Net Income (Loss) per Common Share	Net Income (Loss) per Common Share Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Except where the result would be antidilutive, diluted net income (loss) per common share is calculated by dividing net income (loss) by the sum of the weighted average number of common shares plus common stock equivalents, if applicable. With respect to its convertible debt issued in 2016, Teradyne has determined that it has the ability and intent to settle the principal of the convertible debt in cash; accordingly, the principal amount is excluded from the determination of diluted earnings per share. As a result, Teradyne is accounting for the conversion spread using the treasury stock method.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes net income, unrealized pension and postretirement prior service costs and benefits, unrealized gains and losses on investments in debt and equity marketable securities and foreign currency translation adjustment.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Deferred Revenue and Customer Advances	As of December 31, 2017 and 2016, deferred revenue and customer advances consisted of the following and are included in the short and long-term deferred revenue and customer advances: 2017 2016 (in thousands) Maintenance and training $ 57,256 $ 46,803 Customer advances, undelivered elements and other 32,047 32,938 Extended warranty 24,438 28,200 Total deferred revenue and customer advances $ 113,741 $ 107,941
Warranty Accrual Included in Other Accrued Liabilities	The balance below is included in other accrued liabilities: Amount (in thousands) Balance at December 31, 2014 $ 8,942 Acquisition 409 Accruals for warranties issued during the period 11,539 Accruals related to pre-existing (3,159 ) Settlements made during the period (10,806 ) Balance at December 31, 2015 6,925 Accruals for warranties issued during the period 14,291 Accruals related to pre-existing (1,354 ) Settlements made during the period (12,659 ) Balance at December 31, 2016 7,203 Accruals for warranties issued during the period 14,223 Accruals related to pre-existing (379 ) Settlements made during the period (12,847 ) Balance at December 31, 2017 $ 8,200
Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances	The balance below is included in short and long-term deferred revenue and customer advances: Amount (in thousands) Balance at December 31, 2014 $ 34,197 Acquisition 870 Deferral of new extended warranty revenue 17,698 Recognition of extended warranty deferred revenue (22,741 ) Balance at December 31, 2015 30,024 Deferral of new extended warranty revenue 19,909 Recognition of extended warranty deferred revenue (21,733 ) Balance at December 31, 2016 28,200 Deferral of new extended warranty revenue 20,513 Recognition of extended warranty deferred revenue (24,275 ) Balance at December 31, 2017 $ 24,438
Schedule of Prepayments and Other Current Assets	Prepayments consist of the following and are included in prepayments and other current assets on the balance sheet: 2017 2016 (in thousands) Contract manufacturer and supplier prepayments $ 82,503 $ 84,473 Prepaid maintenance and other services 8,189 7,676 Prepaid taxes 5,039 4,664 Other prepayments 12,386 11,641 Total prepayments $ 108,117 $ 108,454
Useful Lives of Assets	Teradyne provides for depreciation of its assets principally on the straight-line method with the cost of the assets being charged to expense over their useful lives as follows: Buildings 40 years Building improvements 5 to 10 years Leasehold improvements Lesser of lease term or 10 years Furniture and fixtures 10 years Test systems manufactured internally 6 years Machinery and equipment 3 to 5 years Software 3 to 5 years

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Universal Robots
Final Allocation of Purchase Price	The following table represents the final allocation of the purchase price: Purchase Price Allocation (in thousands) Goodwill $ 221,128 Intangible assets 121,590 Tangible assets acquired and liabilities assumed: Current assets 10,853 Non-current 3,415 Accounts payable and current liabilities (11,976 ) Long-term deferred tax liabilities (26,653 ) Long-term other liabilities (2,920 ) Total purchase price $ 315,437
Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date	Components of these intangible assets and their estimated useful lives at the acquisition date are as follows: Fair Value Estimated Useful (in thousands) (in years) Developed technology $ 89,240 4.9 Trademarks and tradenames 22,920 10.0 Customer relationships 9,430 2.0 Total intangible assets $ 121,590 5.6
Avionics Interface Technologies, LLC
Pro Forma Results Under Acquisitions	The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: For the Year Ended December 31, 2015 (in thousands, except per share amounts) Revenue $ 1,657,626 Net income $ 199,784 Net income per common share: Basic $ 0.94 Diluted $ 0.94

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Composition of Inventories, Net	Inventories, net consisted of the following at December 31, 2017 and 2016: 2017 2016 (in thousands) Raw material $ 62,668 $ 58,530 Work-in-process 19,464 22,946 Finished Goods 25,393 54,482 $ 107,525 $ 135,958

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant and Equipment, Net	Property, plant and equipment, net consisted of the following at December 31, 2017 and 2016: 2017 2016 (in thousands) Land $ 16,561 $ 16,561 Buildings 98,369 98,031 Machinery and equipment 647,961 601,835 Furniture and fixtures, and software 88,539 82,897 Leasehold improvements 49,540 46,612 Construction in progress 13,522 3,032 914,492 848,968 Less: accumulated depreciation 646,045 595,147 $ 268,447 $ 253,821

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The following table sets forth by fair value hierarchy Teradyne’s financial assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2017 and 2016: December 31, 2017 Quoted Prices in Active Markets for Identical Instruments (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in thousands) Assets Cash $ 197,955 $ — $ — $ 197,955 Cash equivalents 206,335 25,553 — 231,888 Available for sale securities: U.S. Treasury securities — 855,795 — 855,795 Commercial paper — 282,840 — 282,840 Certificates of deposit and time deposits — 167,342 — 167,342 Corporate debt securities — 133,186 — 133,186 Equity and debt mutual funds 23,430 — — 23,430 U.S. government agency securities — 10,726 — 10,726 Non-U.S. — 586 — 586 $ 427,720 $ 1,476,028 $ — $ 1,903,748 Derivative assets — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Contingent consideration $ — $ — $ 45,102 $ 45,102 Derivative liabilities — 446 — 446 Total $ — $ 446 $ 45,102 $ 45,548 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 404,290 $ 25,553 $ — $ 429,843 Marketable securities — 1,347,979 — 1,347,979 Long-term marketable securities 23,430 102,496 — 125,926 Prepayments — 389 — 389 Total $ 427,720 $ 1,476,417 $ — $ 1,904,137 Liabilities Other current liabilities $ — $ 446 $ — $ 446 Contingent consideration — — 24,497 24,497 Long-term contingent consideration — — 20,605 20,605 Total $ — $ 446 $ 45,102 $ 45,548 December 31, 2016 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 $ 214,722 $ — $ — $ 214,722 Cash equivalents 37,458 55,704 — 93,162 Available for sale securities: U.S. Treasury securities — 902,800 — 902,800 Commercial paper — 161,630 — 161,630 Corporate debt securities — 100,153 — 100,153 Certificates of deposit and time deposits — 82,133 — 82,133 U.S. government agency securities — 39,252 — 39,252 Equity and debt mutual funds 18,171 — — 18,171 Non-U.S. — 728 — 728 $ 270,351 $ 1,342,400 $ — $ 1,612,751 Derivative assets — 1 — 1 Total $ 270,351 $ 1,342,401 $ — $ 1,612,752 Liabilities Contingent consideration $ — $ — $ 38,332 $ 38,332 Derivative liabilities — 131 — 131 Total $ — $ 131 $ 38,332 $ 38,463 Reported as follows: (Level 1) (Level 2) (Level 3) Total (in thousands) Assets Cash and cash equivalents $ 252,180 $ 55,704 $ — $ 307,884 Marketable securities — 871,024 — 871,024 Long-term marketable securities 18,171 415,672 — 433,843 Prepayments — 1 — 1 Total $ 270,351 $ 1,342,401 $ — $ 1,612,752 Liabilities Other current liabilities $ — $ 131 $ — $ 131 Contingent consideration — — 1,050 1,050 Long-term contingent consideration — — 37,282 37,282 Total $ — $ 131 $ 38,332 $ 38,463
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	Changes in the fair value of Level 3 contingent consideration for the years ended December 31, 2017 and 2016 were as follows: Contingent Consideration (in thousands) Balance at December 31, 2015 $ 37,436 Payments (1) (15,000 ) Fair value adjustment of AIT (2) 550 Fair value adjustment of Universal Robots (2) 15,346 Balance at December 31, 2016 38,332 Payments (3) (1,050 ) Fair value adjustment of Universal Robots (4) 7,820 Balance at December 31, 2017 $ 45,102 (1) During the year ended December 31, 2016, based on Universal Robots’ calendar year 2015 EBITDA results, Teradyne paid $15 million or 100% of the eligible EBITDA contingent consideration amount. (2) During the year ended December 31, 2016, the fair value of contingent consideration for the earn-out earn-out (3) During the year ended December 31, 2017, Teradyne paid $1.1 million of contingent consideration for the earn-out (4) During the year ended December 31, 2017, the fair value of contingent consideration for the earn-out
Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument	The following table provides quantitative information associated with the fair value measurement of Teradyne’s Level 3 financial instrument: Liability December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Weighted Average (in thousands) Contingent consideration (Universal Robots) $ 24,497 (1) $ 20,605 Monte Carlo simulation Revenue for the period July 1, 2015—December 31, 2018 volatility 11.2% Discount Rate 3.3% (1) Contingent consideration of $24.5 million is expected to be paid in March 2018.
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The carrying amounts and fair values of financial instruments at December 31, 2017 and 2016 were as follows: December 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value (in thousands) Assets Cash and cash equivalents $ 429,843 $ 429,843 $ 307,884 $ 307,884 Marketable securities 1,473,905 1,473,905 1,304,867 1,304,867 Derivative assets 389 389 1 1 Liabilities Contingent consideration 45,102 45,102 38,332 38,332 Derivative liabilities 446 446 131 131 Convertible debt (1) 365,987 659,525 352,669 486,754 (1) The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features.
Schedule of Available-for-Sale Marketable Securities	The following tables summarize the composition of available for sale marketable securities at December 31, 2017 and 2016: December 31, 2017 Available-for-Sale Fair Market Value of Investments with Unrealized Losses Cost Unrealized Gain Unrealized (Loss) Fair Market Value (in thousands) U.S. Treasury securities $ 858,258 $ 72 $ (2,535 ) $ 855,795 $ 850,163 Commercial paper 283,009 18 (187 ) 282,840 258,933 Certificates of deposit and time deposits 167,523 6 (187 ) 167,342 138,340 Corporate debt securities 131,179 2,380 (373 ) 133,186 91,010 Equity and debt mutual funds 19,403 4,102 (75 ) 23,430 1,723 U.S. government agency securities 10,775 — (49 ) 10,726 10,726 Non-U.S. 582 4 — 586 — $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 1,349,970 $ 38 $ (2,029 ) $ 1,347,979 $ 1,288,844 Long-term marketable securities 120,759 6,544 (1,377 ) 125,926 62,052 $ 1,470,729 $ 6,582 $ (3,406 ) $ 1,473,905 $ 1,350,896 December 31, 2016 Available-for-Sale Fair Market Value of Investments with Unrealized Losses Cost Unrealized Gain Unrealized (Loss) Fair Market Value (in thousands) U.S. Treasury securities $ 904,737 $ 97 $ (2,034 ) $ 902,800 $ 572,284 Commercial paper 161,672 24 (66 ) 161,630 84,034 Corporate debt securities 99,708 1,065 (620 ) 100,153 53,642 Certificates of deposit and time deposits 82,080 54 (1 ) 82,133 7,760 U.S. government agency securities 39,264 7 (19 ) 39,252 13,461 Equity and debt mutual funds 16,505 1,724 (58 ) 18,171 1,661 Non-U.S. 745 6 (23 ) 728 137 $ 1,304,711 $ 2,977 $ (2,821 ) $ 1,304,867 $ 732,979 Reported as follows: Cost Unrealized Gain Unrealized (Loss) Fair Market Value Fair Market Value of Investments with Unrealized Losses (in thousands) Marketable securities $ 871,321 $ 134 $ (431 ) $ 871,024 $ 423,128 Long-term marketable securities 433,390 2,843 (2,390 ) 433,843 309,851 $ 1,304,711 $ 2,977 $ (2,821 ) $ 1,304,867 $ 732,979
Contractual Maturities of Investments Held	The contractual maturities of investments held at December 31, 2017 were as follows: Cost Fair Value (in thousands) Due within one year $ 1,349,970 $ 1,347,979 Due after 1 year through 5 years 48,796 48,599 Due after 5 years through 10 years 13,916 13,489 Due after 10 years 38,644 40,408 Total $ 1,451,326 $ 1,450,475
Non-Financial Assets Measured at Fair Value on Non-Recurring Basis	The following table sets forth by fair value hierarchy Teradyne’s non-financial non-recurring July 3, 2016 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total Total (in thousands) Assets Goodwill $ — $ — $ 7,976 $ 7,976 $ 254,946 Definite lived intangible assets — — 5,750 5,750 83,339 $ — $ — $ 13,726 $ 13,726 $ 338,285 (1) In accordance with the provisions of ASC 350-20, Goodwill (2) In accordance with the provisions of ASC 360-10, “Property, Plant and Equipment”,
Schedule of Notional Amount of Derivatives	At December 31, 2017 and 2016, Teradyne had the following contracts to buy and sell non-U.S. non-U.S. December 31, 2017 December 31, 2016 Buy Position Sell Position Net Total Buy Position Sell Position Net Total (in millions) Japanese Yen $ (35.7 ) $ — $ (35.7 ) $ (17.7 ) $ — $ (17.7 ) Taiwan Dollar (9.9 ) — (9.9 ) (6.9 ) — (6.9 ) Korean Won (8.9 ) — (8.9 ) (8.8 ) — (8.8 ) British Pound Sterling (1.4 ) — (1.4 ) (1.3 ) — (1.3 ) Singapore Dollar — 33.5 33.5 — 24.0 24.0 Euro — 27.4 27.4 — 25.2 25.2 Total $ (55.9 ) $ 60.9 $ 5.0 $ (34.7 ) $ 49.2 $ 14.5
Schedule of Derivative Instruments in Statement of Financial Position at Fair Value	The following table summarizes the fair value of derivative instruments as of December 31, 2017 and 2016: Balance Sheet Location 2017 2016 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Prepayments $ 389 $ 1 Foreign exchange contracts Other current liabilities (446 ) (131 ) Total derivatives $ (57 ) $ (130 )
Schedule of Effect of Derivative Instruments on Statement of Operations Recognized	The following table summarizes the effect of derivative instruments in the statements of operations recognized for the years ended December 31, 2017, 2016, and 2015. Location of (Gains) Losses Recognized in Statement of Operations 2017 2016 2015 (in thousands) Derivatives not designated as hedging instruments: Foreign exchange contracts Other (income) expense, net $ (1,133 ) $ 8,671 $ 3,047 (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 year ended December 31, 2017, net losses from the remeasurement of monetary assets and liabilities denominated in foreign currencies were $2.9 million. (3) For the years ended December 31, 2016, and 2015, net gains from the remeasurement of the monetary assets and liabilities denominated in foreign currencies were $8.0 million and $2.5 million, respectively.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Components of Convertible Senior Notes	The below tables represents the key components of Teradyne’s convertible senior notes: December 31, 2017 December 31, (in thousands) (in thousands) Debt Principal $ 460,000 $ 460,000 Unamortized discount 94,013 107,331 Net Carrying amount of convertible debt $ 365,987 $ 352,669 For the year ended December 31, December 31, (in thousands) (in thousands) Contractual interest expense on the coupon $ 5,734 $ 303 Amortization of the discount component and debt issue fees recognized as interest expense 13,318 688 Total interest expense on the convertible debt $ 19,052 $ 991

Accumulated Other Comprehensi39

Accumulated Other Comprehensive (Loss) Income (Tables)	12 Months Ended
	Dec. 31, 2017
Changes in Accumulated Other Comprehensive (Loss) Income	Changes in accumulated other comprehensive (loss) income, which is presented net of tax, consists of the following: Foreign Currency Translation Adjustment Unrealized Gains (Losses) on Marketable Securities Retirement Plans Prior Service Credit Total (in thousands) Balance at December 31, 2015, net of tax of $0, (459), $(622) $ (8,759 ) $ (1,414 ) $ 2,029 $ (8,144 ) Other comprehensive (loss) income before reclassifications, net of tax of $0, $923, $34 (13,162 ) 2,037 59 (11,066 ) Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(255), $(190) — (683 ) (321 ) (1,004 ) Net current period other comprehensive (loss) income, net of tax of $0, $668, $(156) (13,162 ) 1,354 (262 ) (12,070 ) Balance at December 31, 2016, net of tax of $0, $209, $(778) (21,921 ) (60 ) 1,767 (20,214 ) Other comprehensive income before reclassifications, net of tax of $0, $1,903, $0 37,840 1,863 — 39,703 Amounts reclassified from accumulated other comprehensive income, net of tax of $0, $(297), $(154) — (441 ) (272 ) (713 ) Net current period other comprehensive income, net of tax of $0, $1,606, $(154) 37,840 1,422 (272 ) 38,990 Balance at December 31, 2017, net of tax of $0, $1,815, $(932) $ 15,919 $ 1,362 $ 1,495 $ 18,776
Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations	Reclassifications out of accumulated other comprehensive income to the statements of operations for the years ended December 31, 2017, 2016 and 2015, were as follows: Details about Accumulated Other Comprehensive Income Components For the year ended Affected Line Item in the Statements of Operations December 31, 2017 December 31, 2016 December 31, 2015 (in thousands) Available-for-sale Unrealized gains, net of tax of $297, $255, $390 $ 441 $ 683 $ 704 Interest income Defined benefit pension and postretirement plans: Amortization of prior service benefit, net of tax of $154, $190, $169 272 321 295 (a) Total reclassifications, net of tax of $451, $445, $559 $ 713 $ 1,004 $ 999 Net income (a) The amortization of prior service credit is included in the computation of net periodic pension cost and postretirement benefit; see Note N: “Retirement Plans.”

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by reportable segments for the years ended December 31, 2017 and 2016 are as follows: Industrial Automation System Test Wireless Test Semiconductor Test Total (in thousands) Balance at December 31, 2015: Goodwill $ 214,975 $ 158,699 $ 361,819 $ 260,540 $ 996,033 Accumulated impairment losses — (148,183 ) (98,897 ) (260,540 ) (507,620 ) 214,975 10,516 262,922 — 488,413 Foreign currency translation adjustment (10,124 ) — — — (10,124 ) Goodwill impairment losses — — (254,946 ) — (254,946 ) Balance at December 31, 2016: Goodwill 204,851 158,699 361,819 260,540 985,909 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) 204,851 10,516 7,976 — 223,343 Foreign currency translation adjustment 28,668 — — — 28,668 Balance at December 31, 2017: Goodwill 233,519 158,699 361,819 260,540 1,014,577 Accumulated impairment losses — (148,183 ) (353,843 ) (260,540 ) (762,566 ) $ 233,519 $ 10,516 $ 7,976 $ — $ 252,011
Schedule of Estimated Intangible Assets Amortization Expense	Estimated intangible assets amortization expense for each of the five succeeding fiscal years is as follows: Year Amortization Expense (in thousands) 2018 $ 29,496 2019 25,533 2020 11,249 2021 3,732 2022 2,927 Thereafter 6,151
Wireless Test
Schedule of Amortizable Intangible Assets	Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets: December 31, 2017 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (226,190 ) $ 1,618 $ 46,305 Customer relationships 92,741 (83,585 ) 171 9,327 Tradenames and trademarks 50,100 (27,120 ) 416 23,396 Non-compete 320 (260 ) — 60 Total intangible assets $ 414,038 $ (337,155 ) $ 2,205 $ 79,088 December 31, 2016 Gross Carrying Amount Accumulated Amortization Foreign Net Carrying Amount (in thousands) Developed technology $ 270,877 $ (206,376 ) $ (5,093 ) $ 59,408 Customer relationships 92,741 (76,707 ) (538 ) 15,496 Tradenames and trademarks 50,100 (23,435 ) (1,308 ) 25,357 Non-compete 320 (180 ) — 140 Total intangible assets $ 414,038 $ (306,698 ) $ (6,939 ) $ 100,401

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Non-Cancelable Operating Lease Commitments	The following table reflects Teradyne’s non-cancelable Non-cancelable (in thousands) 2018 $ 17,560 2019 14,355 2020 11,851 2021 9,201 2022 7,331 Beyond 2023 7,425 Total $ 67,723

Net Income (Loss) per Common 42

Net Income (Loss) per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
Computation of Basic and Diluted Net Income (Loss) Per Common Share	The following table sets forth the computation of basic and diluted net income (loss) per common share: 2017 2016 2015 (in thousands, except per share amounts) Net income (loss) for basic and diluted net income per share $ 257,692 $ (43,421 ) $ 206,477 Weighted average common shares-basic 198,069 202,578 211,544 Effect of dilutive potential common shares: Restricted stock units 1,800 — 1,130 Incremental shares from assumed conversion of convertible notes (1) 1,298 — — Stock options 335 — 606 Convertible note hedge warrant shares (2) 112 — — Employee stock purchase rights 27 — 41 Dilutive potential common shares 3,572 — 1,777 Weighted average common shares-diluted 201,641 202,578 213,321 Net income (loss) per common share-basic $ 1.30 $ (0.21 ) $ 0.98 Net income (loss) per common share-diluted $ 1.28 $ (0.21 ) $ 0.97 (1) Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.80, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the convertible debt, was divided by the average Teradyne stock price for the period. (2) Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $39.91, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne’s call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive.

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Pension Plans
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of these defined benefit pension plans assets and obligations are shown below: 2017 2016 United States Foreign United States Foreign (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 353,616 $ 60,738 $ 351,117 $ 62,290 Service cost 2,239 818 2,302 761 Interest cost 13,151 852 13,630 1,185 Actuarial loss 12,702 262 6,053 5,621 Benefits paid (18,682 ) (994 ) (19,486 ) (1,385 ) Settlements — (28,560 ) — — Expenses paid — (40 ) — (609 ) Non-U.S. — 6,277 — (7,125 ) End of year 363,026 39,353 353,616 60,738 Change in plan assets: Fair value of plan assets: Beginning of year 307,304 27,571 298,404 28,141 Company contributions 4,462 883 4,489 867 Actual return on plan assets 31,422 737 23,897 5,142 Benefits paid (18,682 ) (994 ) (19,486 ) (1,148 ) Settlements — (28,560 ) — — Expenses paid — (40 ) — (609 ) Non-U.S. — 1,710 — (4,822 ) End of year 324,506 1,307 307,304 27,571 Funded status $ (38,520 ) $ (38,046 ) $ (46,312 ) $ (33,167 )
Amounts Recorded within Statement of Financial Position	The following table provides amounts recorded within the account line items of the statements of financial position as of December 31: 2017 2016 United States Foreign United States Foreign (in thousands) Retirement plans assets $ 17,491 $ — $ 7,712 $ — Accrued employees’ compensation and withholdings (2,524 ) (863 ) (2,591 ) (772 ) Retirement plans liabilities (53,487 ) (37,183 ) (51,433 ) (32,395 ) Funded status $ (38,520 ) $ (38,046 ) $ (46,312 ) $ (33,167 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2017 2016 United States Foreign United States Foreign (in thousands) Prior service cost, before tax $ 58 $ — $ 127 $ — Deferred taxes 539 — 514 — Total recognized in other comprehensive income, net of tax $ 597 $ — $ 641 $ —
Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets	Information for pension plans with an accumulated benefit obligation in excess of plan assets as of December 31: 2017 2016 United States Foreign United States Foreign (in millions) Projected benefit obligation $ 56.0 $ 39.4 $ 54.0 $ 34.3 Accumulated benefit obligation 51.6 34.7 48.0 30.1 Fair value of plan assets — 1.3 — 1.1
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2017, 2016, and 2015, Teradyne’s net periodic pension (income) cost was comprised of the following: 2017 2016 2015 United States Foreign United States Foreign United States Foreign (in thousands) Components of Net Periodic Pension (Income) Cost: Service cost $ 2,239 $ 818 $ 2,302 $ 761 $ 2,462 $ 1,006 Interest cost 13,151 852 13,630 1,185 13,142 1,444 Expected return on plan assets (12,008 ) (165 ) (13,830 ) (443 ) (14,517 ) (781 ) Amortization of prior service cost 70 — 96 — 134 — Net actuarial (gain) loss (6,712 ) (310 ) (4,013 ) 815 10,596 8,415 Curtailment — — — — — (634 ) Total net periodic pension (income) cost $ (3,260 ) $ 1,195 $ (1,815 ) $ 2,318 $ 11,817 $ 9,450 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Reversal of amortization items: Prior service cost (70 ) — (96 ) — (134 ) — Total recognized in other comprehensive income (70 ) — (96 ) — (134 ) — Total recognized in net periodic pension (income) cost and other comprehensive income $ (3,330 ) $ 1,195 $ (1,911 ) $ 2,318 $ 11,683 $ 9,450
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Pension Cost at January 1: 2017 2016 2015 United States Foreign United States Foreign United States Foreign Discount rate 3.9 % 1.8 % 4.0 % 2.3 % 3.7 % 2.6 % Expected return on plan assets 4.0 2.0 4.8 2.0 4.8 2.6 Salary progression rate 2.6 2.7 2.7 3.2 2.9 3.2 Weighted Average Assumptions to Determine Pension Obligations at December 31: 2017 2016 United States Foreign United States Foreign Discount rate 3.4 % 1.8 % 3.9 % 1.8 % Salary progression rate 2.3 2.7 2.6 2.7
Weighted Average Pension Asset Allocations by Category	The following table provides weighted average pension asset allocation by asset category at December 31, 2017 and 2016: 2017 2016 United States Foreign United States Foreign Fixed income securities 88.1 % — % 88.1 % — % Equity securities 9.9 — 9.9 — Other 2.0 100.0 2.0 100.0 100.0 % 100.0 % 100.0 % 100.0 %
Target Asset Allocation and Index for Each Asset Category	The target asset allocation and the index for each asset category for the U.S. Plan, per the investment policy, are as follows: Asset Category: Policy Index: Target Allocation U.S. corporate fixed income Bloomberg Barclays U.S. Corporate A or Better Index 76 % Global equity MSCI World Minimum Volatility Index 10 U.S. government fixed income Bloomberg Barclays U.S. Long Government Bond Index 8 High yield fixed income Bloomberg Barclays U.S. Corporate High Yield 2% Issuer Cap Index 5 Cash Citigroup Three Month U.S. Treasury Bill Index 1
Changes in Fair Value of Pension Assets	The fair value of pension plan assets by asset category and by level at December 31, 2017 and December 31, 2016 were as follows: December 31, 2017 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 260,294 $ — $ 260,294 $ — $ — $ — $ — U.S. government debt securities — 25,709 — 25,709 — — — — Global equity — 32,120 — 32,120 — — — — Group annuity insurance contracts — — 3,166 3,166 — — — — Other — — — — — 1,307 — 1,307 Cash and cash equivalents 3,217 — — 3,217 — — — — Total $ 3,217 $ 318,123 $ 3,166 $ 324,506 $ — $ 1,307 $ — $ 1,307 The pension plan assets identified as Level 3 above are related to group annuity insurance contracts held by the U.S. Plan. The fair value of these assets was calculated using the present value of future pension payments due under the group annuity insurance contracts. December 31, 2016 United States Foreign Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in thousands) Fixed income securities: Corporate debt securities $ — $ 246,528 $ — $ 246,528 $ — $ — $ — $ — U.S. government debt securities — 24,322 — 24,322 — — — — Global equity — 30,360 — 30,360 — — — — Group annuity insurance contracts — — 3,071 3,071 — — 26,385 26,385 Other — — — — — 1,124 — 1,124 Cash and cash equivalents 3,023 — — 3,023 62 — — 62 Total $ 3,023 $ 301,210 $ 3,071 $ 307,304 $ 62 $ 1,124 $ 26,385 $ 27,571
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: United States Foreign (in thousands) 2018 $ 19,387 $ 886 2019 19,022 887 2020 19,688 1,253 2021 20,246 1,002 2022 20,994 952 2023-2027 110,214 6,294
Group Annuity Insurance Contracts
Changes in Fair Value of Pension Assets	Changes in the fair value of Level 3 group annuity insurance contracts for the years ended December 31, 2017 and 2016 were as follows: Group Annuity Insurance Contracts (in thousands) Balance at December 31, 2015 $ 29,392 Purchases of group annuity insurance contracts 709 Interest and market value adjustments 5,308 Benefits paid (611 ) Other (634 ) Non-U.S. (4,708 ) Balance at December 31, 2016 29,456 Settlements (28,560 ) Interest and market value adjustments 959 Benefits paid (244 ) Other (61 ) Non-U.S. 1,616 Balance at December 31, 2017 $ 3,166
Postretirement Benefit Plans
Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligations	The December 31 balances of the postretirement assets and obligations are shown below: 2017 2016 (in thousands) Assets and Obligations Change in benefit obligation: Projected benefit obligation: Beginning of year $ 5,510 $ 6,030 Service cost 34 37 Interest cost 201 218 Actuarial loss 398 5 Special termination benefits 591 — Benefits paid (557 ) (687 ) Plan amendments — (93 ) End of year 6,177 5,510 Change in plan assets: Fair value of plan assets: Beginning of year — — Company contributions 557 687 Benefits paid (557 ) (687 ) End of year — — Funded status $ (6,177 ) $ (5,510 )
Amounts Recorded within Statement of Financial Position	The following table provides amounts recorded within the account line items of financial position as of December 31: 2017 2016 (in thousands) Accrued employees’ compensation and withholdings $ (591 ) $ (571 ) Retirement plans liability (5,586 ) (4,939 ) Funded status $ (6,177 ) $ (5,510 )
Amounts Recognized in Accumulated Other Comprehensive Income	The following table provides amounts recognized in accumulated other comprehensive income as of December 31: 2017 2016 (in thousands) Prior service credit, before tax $ (622 ) $ (1,118 ) Deferred taxes (1,472 ) (1,292 ) Total recognized in other comprehensive income, net of tax $ (2,094 ) $ (2,410 )
Net Periodic Pension and Postretirement Benefit Costs	For the years ended December 31, 2017, 2016, and 2015, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following: 2017 2016 2015 (in thousands) Components of Net Periodic Postretirement Benefit Cost (income): Service cost $ 34 $ 37 $ 48 Interest cost 201 218 237 Amortization of prior service credit (496 ) (607 ) (598 ) Net actuarial loss (gain) 398 5 (648 ) Special termination benefits 591 — — Total net periodic postretirement benefit cost (income) 728 (347 ) (961 ) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income: Prior service cost — (93 ) — Reversal of amortization items: Prior service credit 496 607 598 Total recognized in other comprehensive income 496 514 598 Total recognized in net periodic postretirement cost (income) and other comprehensive income $ 1,224 $ 167 $ (363 )
Weighted Average Assumptions to Determine Net Periodic Cost and Benefit Obligation	Weighted Average Assumptions to Determine Net Periodic Postretirement Benefit Income as of January 1: 2017 2016 2015 Discount rate 3.9 % 3.9 % 3.5 % Initial health care cost trend rate 7.3 7.5 7.5 Ultimate health care cost trend rate 5.0 5.0 5.0 Year in which ultimate health care cost trend rate is reached 2023 2023 2022 Weighted Average Assumptions to Determine Postretirement Benefit Obligation as of December 31: 2017 2016 2015 Discount rate 3.4 % 3.9 % 3.9 % Initial medical trend 7.9 7.3 7.5 Ultimate health care trend 4.5 5.0 5.0 Medical cost trend rate decrease to ultimate rate in year 2026 2023 2023
Expected Future Benefit Payments	Future benefit payments are expected to be paid as follows: Benefit Payments (in thousands) 2018 $ 591 2019 597 2020 535 2021 502 2022 439 2023-2027 1,665
One Percentage Point Change in Assumed Health Care Cost Trend Rates for Year	A one percentage point change in the assumed health care cost trend rates for the year ended December 31, 2017 would have the following effects: 1 Percentage Point Increase 1 Percentage Point Decrease (in thousands) Effect on total service and interest cost components $ 3 $ (3 ) Effect on postretirement benefit obligations 64 (60 )

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
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: 2017 2016 2015 Risk-free interest rate 1.5 % 1.0 % 0.8 % Teradyne volatility-historical 26.6 % 27.0 % 28.2 % NYSE Composite Index volatility-historical 13.4 % 13.1 % — Philadelphia Semiconductor Index volatility-historical — — 19.7 % Dividend yield 1.0 % 1.2 % 1.3 %
Fair Value of Stock Options Using Assumptions	The fair value of the stock options at grant date was estimated using the Black-Scholes option-pricing model with the following assumptions: 2017 2016 2015 Expected life (years) 5.0 5.0 4.0 Risk-free interest rate 2.0 % 1.4 % 1.1 % Volatility-historical 27.8 % 32.9 % 33.4 % Dividend yield 1.0 % 1.2 % 1.3 %
Stock Compensation Plan Activity	Stock compensation plan activity for the years 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Restricted Stock Units: Non-vested 3,778 4,070 4,352 Awarded 939 1,471 1,681 Vested (1,434 ) (1,530 ) (1,679 ) Forfeited (109 ) (233 ) (284 ) Non-vested 3,174 3,778 4,070 Stock Options: Outstanding at January 1 926 1,121 1,507 Granted 111 130 132 Exercised (501 ) (324 ) (518 ) Forfeited — — — Expired (5 ) (2 ) — Outstanding at December 31 531 926 1,121 Vested and expected to vest at December 31 531 926 1,121 Exercisable at December 31 233 598 779
Share Based Compensation Total Shares Available	Total shares available for the years 2017, 2016, and 2015: 2017 2016 2015 (in thousands) Shares available: Available for grant at January 1 9,546 10,914 12,443 Options granted (111 ) (130 ) (132 ) Restricted stock units awarded (939 ) (1,471 ) (1,681 ) Restricted stock units forfeited 109 233 284 Additional shares reserved — — — Available for grant at December 31 8,605 9,546 10,914
Weighted-Average Restricted Stock Unit Award Date Fair Value	Weighted average restricted stock unit award date fair value information for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Non-vested $ 18.27 $ 17.66 $ 17.35 Awarded 28.91 18.95 17.66 Vested 17.90 17.36 16.93 Forfeited 20.35 17.80 17.28 Non-vested $ 21.71 $ 18.27 $ 17.66
Restricted Stock Unit Awards Aggregate Intrinsic Value	Restricted stock unit awards aggregate intrinsic value information at December 31 for the years 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Vested $ 40,649 $ 30,008 $ 32,200 Outstanding 132,875 95,952 84,129 Expected to vest 130,594 91,871 79,611
Restricted Stock Units Weighted Average Remaining Contractual Terms	Restricted stock units weighted average remaining contractual terms (in years) information at December 31, for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Outstanding 1.00 1.04 1.09 Expected to vest 0.99 1.03 1.08
Weighted Average Stock Options Exercise Price	Weighted average stock options exercise price information for the year ended December 31, 2017 follows: 2017 Outstanding at January 1 $ 11.93 Options granted 28.56 Options exercised 13.60 Options forfeited 3.04 Options cancelled — Outstanding at December 31 13.92 Exercisable at December 31 2.95
Stock Option Aggregate Intrinsic Value Information	Stock option aggregate intrinsic value information for the years ended December 31, 2017, 2016, and 2015 follows: 2017 2016 2015 (in thousands) Exercised $ 8,035 $ 3,729 $ 7,255 Outstanding 14,831 12,468 11,729 Vested and expected to vest 14,831 12,468 11,729 Exercisable 9,076 10,217 10,716
Stock Options Weighted Average Remaining Contractual Terms	Stock options weighted average remaining contractual terms (in years) information at December 31, for the years 2017, 2016, and 2015 follows: 2017 2016 2015 Outstanding 4.1 3.9 4.2 Vested and expected to vest 4.1 3.9 4.2 Exercisable 2.8 3.2 3.9
Significant Option Groups Outstanding	Significant option groups outstanding at December 31, 2017 and related weighted average price and remaining contractual life information follow: Options Outstanding Options Exercisable Range Of Exercise Prices Weighted- Average Remaining Contractual Life (Years) Shares Weighted- Average Exercise Price Shares Weighted- Average Exercise Price (shares in thousands) $1.48 – $2.58 2.19 99 $ 1.81 99 $ 1.81 $2.67 – $7.71 3.17 126 2.89 126 2.89 $18.10 – $19.43 4.48 194 18.91 8 18.51 $28.56 6.08 112 28.56 — — 531 $ 13.92 233 $ 2.95
Effect to Income (Loss) from Operations for Recording Stock-Based Compensation	The effect to income from operations for recording stock-based compensation for the years ended December 31 was as follows: 2017 2016 2015 (in thousands) Cost of revenues $ 3,212 $ 3,153 $ 3,065 Engineering and development 9,370 9,458 9,362 Selling and administrative 21,515 18,139 18,024 Stock-based compensation 34,097 30,750 30,451 Income tax benefit (10,462 ) (8,752 ) (8,528 ) Total stock-based compensation expense after income taxes $ 23,635 $ 21,998 $ 21,923

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule of Income (Loss) Before Income Taxes and Provision (Benefit) for Income Taxes from Operations	The components of income (loss) before income taxes and the provision (benefit) for income taxes as shown in the consolidated statements of operations were as follows: 2017 2016 2015 (in thousands) Income (loss) before income taxes: U.S. $ 76,699 $ (341,018 ) $ 56,270 Non-U.S. 447,713 285,958 196,854 $ 524,412 $ (55,060 ) $ 253,124 Provision (benefit) for income taxes: Current: U.S. Federal $ 162,679 $ 7,750 $ 16,635 Non-U.S. 64,313 41,579 35,707 State 2,623 1,968 1,429 229,615 51,297 53,771 Deferred: U.S. Federal 43,687 (51,482 ) (574 ) Non-U.S. (6,476 ) (9,240 ) (7,761 ) State (106 ) (2,214 ) 1,211 37,105 (62,936 ) (7,124 ) Total provision (benefit) for income taxes: $ 266,720 $ (11,639 ) $ 46,647
Reconciliation of Effective Tax Rate	A reconciliation of the effective tax rate for the years 2017, 2016, and 2015 is as follows: 2017 2016 2015 U.S. statutory federal tax rate 35.0 % 35.0 % 35.0 % U.S. transition tax 28.7 — — Impact of rate change on deferred tax 6.4 — — Uncertain tax positions 1.7 (2.6 ) 2.2 Foreign taxes (16.3 ) 78.0 (13.8 ) Foreign tax credits (2.2 ) 49.1 (2.7 ) U.S. research and development credit (1.6 ) 15.8 (3.0 ) Equity compensation (0.8 ) (2.7 ) 0.6 Domestic production activities deduction (0.3 ) 2.3 (1.0 ) State income taxes, net of federal tax benefit — 2.3 0.4 Goodwill impairment — (162.1 ) — U.S. alternative minimum tax credit — 3.7 — Inventory cost capitalization — 1.8 — Other, net 0.3 0.5 0.7 50.9 % 21.1 % 18.4 %
Deferred Tax Assets (Liabilities)	Significant components of Teradyne’s deferred tax assets (liabilities) as of December 31, 2017 and 2016 were as follows: 2017 2016 (in thousands) Deferred tax assets: Tax credits $ 76,083 $ 57,313 Accruals 27,508 27,247 Pension liabilities 22,602 31,581 Inventory valuations 17,793 31,227 Deferred revenue 9,016 12,806 Equity compensation 6,861 9,922 Net operating loss carryforwards 5,440 5,244 Vacation accrual 4,747 7,874 Other 713 630 Gross deferred tax assets 170,763 183,844 Less: valuation allowance (63,919 ) (48,369 ) Total deferred tax assets $ 106,844 $ 135,475 Deferred tax liabilities: Intangible assets $ (16,120 ) $ (22,887 ) Depreciation (12,293 ) (17,117 ) Marketable securities (1,125 ) (210 ) Total deferred tax liabilities $ (29,538 ) $ (40,214 ) Net deferred assets $ 77,306 $ 95,261
Operating Loss Carryforwards	At December 31, 2017, Teradyne had operating loss carryforwards that expire in the following years: U.S. Federal Operating Loss Carryforwards State Operating Loss Carryforwards Foreign Operating Loss Carryforwards (in thousands) 2018 $ — $ 9,943 $ — 2019 — 174 — 2020 — 130 — 2021 — 2,919 — 2022 — 6,362 — 2023-2027 — 12,296 — 2028-2032 — 34,963 — Beyond 2032 — 4,516 130 Non-expiring — — 7,012 Total $ — $ 71,303 $ 7,142
Unrecognized Tax Benefits	Teradyne’s gross unrecognized tax benefits for the years ended December 31, 2017, 2016 and 2015 were as follows: 2017 2016 2015 (in thousands) Beginning balance, as of January 1 $ 38,958 $ 36,792 $ 30,418 Additions: Tax positions for current year 8,208 9,766 6,626 Tax positions for prior years 199 187 792 Reductions: Tax positions for prior years (10,573 ) (1,960 ) (708 ) Expiration of statutes (325 ) (3,532 ) — Settlements with tax authorities (204 ) (2,295 ) (336 ) Ending balance as of December 31 $ 36,263 $ 38,958 $ 36,792

Operating Segment, Geographic46

Operating Segment, Geographic and Significant Customer Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Information	Segment information for the years ended December 31, 2017, 2016, and 2015 is as follows: Semiconductor Test System Test Industrial Automation Wireless Test Corporate And Eliminations Consolidated (in thousands) 2017 Revenues $ 1,662,549 $ 192,135 $ 170,056 $ 111,866 $ — $ 2,136,606 Income (loss) before taxes (1)(2) 491,361 10,306 8,763 17,350 (3,368 ) 524,412 Total assets (3) 597,480 97,018 368,037 59,912 1,987,098 3,109,545 Property additions 87,920 5,976 7,044 4,435 — 105,375 Depreciation and amortization expense 58,901 6,646 25,711 5,392 11,425 108,075 2016 Revenues $ 1,368,169 $ 189,846 $ 99,031 $ 96,204 $ — $ 1,753,250 Income (loss) before taxes (1)(2) 311,939 28,916 (16,783 ) (371,409 ) (7,723 ) (55,060 ) Total assets (3) 557,546 110,361 317,635 62,366 1,714,585 2,762,493 Property additions 70,543 3,788 6,755 4,186 — 85,272 Depreciation and amortization expense 58,087 6,551 26,869 25,921 2,581 120,009 2015 Revenues $ 1,201,530 $ 211,584 $ 41,892 $ 184,572 $ — $ 1,639,578 Income (loss) before taxes (1)(2) 260,154 25,101 (7,574 ) (13,830 ) (10,727 ) 253,124 Total assets (3) 610,869 102,547 344,260 427,880 1,063,118 2,548,674 Property additions 79,052 6,228 1,465 3,133 — 89,878 Depreciation and amortization expense 64,415 4,391 14,500 53,440 4,027 140,773 (1) Included in Corporate and Eliminations are: contingent consideration adjustments, pension and postretirement plans actuarial gains (losses), severance charges, impairment of fixed assets and expenses related to the Japan earthquake, property insurance recovery, interest income, interest expense, net foreign exchange gains (losses), and gain from the sale of an equity investment. (2) Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges, goodwill impairment charges and an acquired intangible assets impairment charge. (3) Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.
Revenues by Country	Information as to Teradyne’s revenues by country is as follows: 2017 2016 2015 (in thousands) Revenues from customers (1): Taiwan $ 687,031 $ 653,076 $ 436,389 China 260,451 174,876 264,898 United States 252,516 221,948 217,386 Korea 206,819 147,882 120,224 Japan 169,093 135,978 128,228 Europe 163,715 117,671 111,903 Malaysia 124,048 103,472 76,707 Philippines 105,850 54,705 96,103 Singapore 101,085 73,172 105,216 Thailand 29,566 43,097 59,104 Rest of the World 36,432 27,373 23,420 $ 2,136,606 $ 1,753,250 $ 1,639,578 (1) Revenues attributable to a country are based on location of customer site.
Long-Lived Assets by Geographic Area	Long-lived assets by geographic area: United States Foreign(1) Total (in thousands) December 31, 2017 $ 198,855 $ 69,592 $ 268,447 December 31, 2016 $ 189,195 $ 64,626 $ 253,821 (1) As of December 31, 2017 and 2016, long-lived assets attributable to Singapore were $23.6 million and $31.5 million, respectively.
Wireless Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Wireless Test segment are charges in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 2,190 $ 7,207 $ 2,500 Restructuring and other—lease impairment 973 — — Restructuring and other—employee severance — 2,650 — Goodwill impairment charge — 254,946 — Intangible assets impairment charge — 83,339 —
System Test
Schedule of Segment Reporting Information by Segment Charges	Included in the System Test segment are charges and credits in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 1,918 $ 630 $ 8,324 Restructuring and other—employee severance — (49 ) 1,037
Semiconductor Test
Schedule of Segment Reporting Information by Segment Charges	Included in the Semiconductor Test segment are charges in the following accounts: For the Year Ended 2017 2016 2015 (in thousands) Cost of revenues—inventory charge $ 4,606 $ 9,656 $ 10,508 Restructuring and other—employee severance 1,779 2,860 499 Restructuring and other—impairment of fixed assets 1,124 — —
Corporate And Eliminations
Schedule of Segment Reporting Information by Segment Charges	Included in the Corporate and Eliminations segment are charges and credits in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Restructuring and other—Universal Robots contingent consideration adjustment $ 7,820 $ 15,346 $ 5,339 Restructuring and other—impairment of fixed assets and expenses related to Japan earthquake 755 5,051 — Restructuring and other—employee severance 530 — — Restructuring and other—property insurance recovery (5,064 ) (5,051 ) — Cost of revenues—pension actuarial (gains) losses (2,752 ) (1,025 ) 8,271 Engineering and development—pension actuarial (gains) losses (2,456 ) (1,234 ) 4,658 Selling and administrative—pension actuarial (gains) losses (1,416 ) (944 ) 4,826 Restructuring and other—ZTEC contingent consideration adjustment — — (1,600 ) Restructuring and other—AIT contingent consideration adjustment — 550 (1,250 ) Restructuring and other—acquisition costs — — 1,104 Other (income) expense, net—gain from the sale of an equity investment — — (5,406 )
Industrial Automation
Schedule of Segment Reporting Information by Segment Charges	Included in the Industrial Automation segment are charges in the following accounts: For the Year Ended December 31, 2017 2016 2015 (in thousands) Restructuring and other—employee severance $ 1,414 $ 585 $ — Cost of revenues—inventory step-up — — 1,567 (1) Included in the cost of revenues for the year ended December 31, 2015 is the cost for purchase accounting inventory step-up.

Supplementary Information (Tabl

Supplementary Information (Tables)	12 Months Ended
	Dec. 31, 2017
Consolidated Quarterly Statements of Operations	The following sets forth certain unaudited consolidated quarterly statements of operations data for each of Teradyne’s last eight quarters. In management’s opinion, this quarterly information reflects all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement for the periods presented. Such quarterly results are not necessarily indicative of future results of operations and should be read in conjunction with the audited consolidated financial statements of Teradyne and the notes thereto included elsewhere herein. 2017 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1) (2)(5) (3) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 373,204 $ 610,356 $ 412,854 $ 388,282 Services 83,709 86,545 90,524 91,133 Total revenues 456,913 696,901 503,378 479,415 Cost of revenues: Cost of products 154,966 267,171 169,744 166,667 Cost of services 37,014 38,511 38,848 39,813 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 191,980 305,682 208,592 206,480 Gross profit 264,933 391,219 294,786 272,935 Operating expenses: Selling and administrative 84,906 89,131 86,244 88,006 Engineering and development 76,182 81,728 77,190 70,564 Acquired intangible assets amortization 7,952 8,166 7,028 7,384 Restructuring and other 2,511 2,288 (4,407 ) 8,970 Total operating expenses 171,551 181,313 166,055 174,924 Income from operations 93,382 209,906 128,731 98,011 Non-operating Interest income (3,520 ) (3,292 ) (4,517 ) (6,476 ) Interest expense 5,402 5,509 5,372 5,380 Other (income) expense, net (516 ) 812 439 1,023 Income before income taxes 92,016 206,877 127,437 98,084 Income tax provision 6,795 31,901 24,017 204,007 Net income (loss) $ 85,221 $ 174,976 $ 103,420 $ (105,923 ) Net income (loss) per common share—basic $ 0.43 $ 0.88 $ 0.52 $ (0.54 ) Net income (loss) per common share—diluted $ 0.42 $ 0.87 $ 0.52 $ (0.54 ) Cash dividend declared per common share $ 0.07 $ 0.07 $ 0.07 $ 0.07 (1) Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges. (2) Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges. (3) Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges. (4) Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets. (5) Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy. 2016 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter (1)(5) (2)(5) (3)(5) (4)(5) (in thousands, except per share amounts) Revenues: Products $ 358,139 $ 456,832 $ 334,610 $ 303,667 Services 72,855 74,960 75,865 76,322 Total revenues 430,994 531,792 410,475 379,989 Cost of revenues: Cost of products 167,555 215,795 148,266 127,481 Cost of services 33,107 33,127 34,850 33,502 Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below) 200,662 248,922 183,116 160,983 Gross profit 230,332 282,870 227,359 219,006 Operating expenses: Selling and administrative 79,174 81,425 78,794 76,289 Engineering and development 73,464 76,109 71,400 70,052 Acquired intangible assets amortization 19,994 16,244 8,487 7,923 Acquired intangible assets impairment — 83,339 — — Goodwill impairment — 254,946 — — Restructuring and other 1,587 2,608 12,177 5,570 Total operating expenses 174,219 514,671 170,858 159,834 Income (loss) from operations 56,113 (231,801 ) 56,501 59,172 Non-operating Interest income (1,642 ) (1,666 ) (2,892 ) (3,095 ) Interest expense 710 691 633 1,604 Other (income) expense, net (147 ) (9 ) (921 ) 1,779 Income (loss) before income taxes 57,192 (230,817 ) 59,681 58,884 Income tax provision (benefit) 7,206 (7,271 ) (4,113 ) (7,461 ) Net income (loss) $ 49,986 $ (223,546 ) $ 63,794 $ 66,345 Net income (loss) per common share—basic $ 0.24 $ (1.10 ) $ 0.32 $ 0.33 Net income (loss) per common share—diluted $ 0.24 $ (1.10 ) $ 0.31 $ 0.33 Cash dividend declared per common share $ 0.06 $ 0.06 $ 0.06 $ 0.06 (1) Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (2) Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake. (3) Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (4) Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration. (5) Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

The Company - Additional inform

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

Deferred Revenue and Customer A

Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Revenue Arrangement
Maintenance and training	$ 57,256	$ 46,803
Customer advances, undelivered elements and other	32,047	32,938
Extended warranty	24,438	28,200	$ 30,024	$ 34,197
Total deferred revenue and customer advances	$ 113,741	$ 107,941

Warranty Accrual Included in Ot

Warranty Accrual Included in Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 7,203	$ 6,925	$ 8,942
Acquisition			409
Accruals for warranties issued during the period	14,223	14,291	11,539
Accruals related to pre-existing warranties	(379)	(1,354)	(3,159)
Settlements made during the period	(12,847)	(12,659)	(10,806)
Balance at end of period	$ 8,200	$ 7,203	$ 6,925

Extended Product Warranty Inclu

Extended Product Warranty Included in Short and Long-Term Deferred Revenue and Customer Advances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Warranty Liability [Line Items]
Balance at beginning of period	$ 28,200	$ 30,024	$ 34,197
Acquisition			870
Deferral of new extended warranty revenue	20,513	19,909	17,698
Recognition of extended warranty deferred revenue	(24,275)	(21,733)	(22,741)
Balance at end of period	$ 24,438	$ 28,200	$ 30,024

Schedule of Prepayments and Oth

Schedule of Prepayments and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepaid And Other Current Assets [Line Items]
Contract manufacturer and supplier prepayments	$ 82,503	$ 84,473
Prepaid maintenance and other services	8,189	7,676
Prepaid taxes	5,039	4,664
Other prepayments	12,386	11,641
Total prepayments	$ 108,117	$ 108,454

Useful Lives of Assets (Detail)

Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	40 years
Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years
Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful lives, description	Lesser of lease term or 10 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	10 years
Test Systems Manufactured Internally
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	6 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	3 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years
Software | Minimum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	3 years
Software | Maximum
Property, Plant and Equipment [Line Items]
Useful lives, maximum years	5 years

Accounting Policies - Additiona

Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

[1],[2]

Oct. 01, 2017

[3]

Jul. 02, 2017

[2],[4]

Apr. 02, 2017

Dec. 31, 2016

[6],[7]

Oct. 02, 2016

[7],[8]

Jul. 03, 2016

[7],[9]

Apr. 03, 2016

[7],[10]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Summary Of Significant Accounting Policies [Line Items]

Depreciation over life to cost of revenues and selling and administrative expenses, years

6 years

Net book value of internally manufactured test systems sold

$ 3,600

$ 11,400

$ 50,700

Income tax provision (benefit)

$ 204,007

$ 24,017

$ 31,901

$ 6,795

[5]

$ (7,461)

$ (4,113)

$ (7,271)

$ 7,206

266,720

(11,639)

46,647

Advertising costs

9,100

6,400

3,300

Losses (gains) on foreign currency transactions

2,900

$ (8,000)

$ (2,500)

ASU 2016-09

Summary Of Significant Accounting Policies [Line Items]

Cumulative effect adjustment to increase retained earnings and deferred tax assets

$ 39,000

Income tax provision (benefit)

$ (6,300)

[1]

Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.

[2]

Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[3]

Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.

[4]

Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.

[5]

Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.

[6]

Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[7]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[8]

Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[9]

Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.

[10]

Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Recently Issued Accounting Pr55

Recently Issued Accounting Pronouncements - Additional Information (Detail) - ASU 2014-09 - Software Licenses - Subsequent Event	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle
Retained earnings adjustment	$ 12,000,000
Income tax expense	(3,000,000)
Sales
New Accounting Pronouncements or Change in Accounting Principle
Effect of Change in Accounting Principle	16,000,000
Cost of revenues | Maximum
New Accounting Pronouncements or Change in Accounting Principle
Effect of Change in Accounting Principle	$ (1,000,000)

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($)	Jun. 11, 2015	Mar. 31, 2016	Oct. 04, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2018
Business Acquisition [Line Items]
Payments of contingent consideration				$ 1,050,000	$ 11,697,000
Universal Robots
Business Acquisition [Line Items]
Total purchase price	$ 315,437,000
Cash paid to acquire outstanding common and preferred stock	283,800,000
Contingent consideration	31,600,000
Arrangement range of outcomes value high	65,000,000
Payments of contingent consideration		$ 15,000,000			$ 15,000,000
EBITDA contingent consideration amount, percentage		100.00%			100.00%
Maximum payment per earn-out				$ 25,000,000
Goodwill, not deductible for tax purposes	$ 221,100,000
Revenues			$ 41,900,000
Income (loss) before income taxes			$ (7,600,000)
Net income						$ 199,784,000
Universal Robots | Subsequent Event
Business Acquisition [Line Items]
Contingent consideration							$ 24,500,000
Universal Robots | Fair Value Adjustment to Inventory
Business Acquisition [Line Items]
Net income						1,600,000
Universal Robots | Acquisition Related Costs
Business Acquisition [Line Items]
Net income						$ 1,000,000

Allocation of Final Purchase Pr

Allocation of Final Purchase Price (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 11, 2015
Business Acquisition [Line Items]
Goodwill	$ 252,011	$ 223,343	$ 488,413
Universal Robots
Business Acquisition [Line Items]
Goodwill				$ 221,128
Intangible assets				121,590
Current assets				10,853
Non-current assets				3,415
Accounts payable and current liabilities				(11,976)
Long-term deferred tax liabilities				(26,653)
Long-term other liabilities				(2,920)
Total purchase price				$ 315,437

Components of Intangible Assets

Components of Intangible Assets and Their Estimated Useful Lives at Acquisition Date (Detail) - Universal Robots $ in Thousands	Jun. 11, 2015USD ($)
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 121,590
Total intangible assets, estimated useful life, years	5 years 7 months 6 days
Developed technology
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 89,240
Total intangible assets, estimated useful life, years	4 years 10 months 25 days
Trademarks and tradenames
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 22,920
Total intangible assets, estimated useful life, years	10 years
Customer Relationships
Business Acquisition [Line Items]
Total intangible assets, fair value	$ 9,430
Total intangible assets, estimated useful life, years	2 years

Pro Forma Results Under Acquisi

Pro Forma Results Under Acquisition (Detail) - Universal Robots $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / shares
Business Acquisition [Line Items]
Revenue | $	$ 1,657,626
Net income | $	$ 199,784
Net income per common share, basic | $ / shares	$ 0.94
Net income per common share, diluted | $ / shares	$ 0.94

Composition of Inventories, Net

Composition of Inventories, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory [Line Items]
Raw material	$ 62,668	$ 58,530
Work-in-process	19,464	22,946
Finished Goods	25,393	54,482
Inventories, net	$ 107,525	$ 135,958

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory [Line Items]
Inventory reserves	$ 102.9	$ 116

Property Plant and Equipment, N

Property Plant and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Land	$ 16,561	$ 16,561
Buildings	98,369	98,031
Machinery and equipment	647,961	601,835
Furniture and fixtures, and software	88,539	82,897
Leasehold improvements	49,540	46,612
Construction in progress	13,522	3,032
Property, Plant and Equipment, Gross, Total	914,492	848,968
Less: accumulated depreciation	646,045	595,147
Property, plant and equipment, net	$ 268,447	$ 253,821

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation of property, plant and equipment	$ 66,122	$ 64,782	$ 68,181
Machinery and equipment	647,961	601,835
Accumulated depreciation	646,045	595,147
Test Systems Leased By Customers
Property, Plant and Equipment [Line Items]
Machinery and equipment	18,100	19,400
Accumulated depreciation	$ 13,700	$ 10,500

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized loss			$ 300,000	$ 500,000	$ 400,000
Available-for-sale securities, realized gain			1,100,000	1,600,000	1,700,000
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses			1,350,896,000	732,979,000
Fair market value of investments with unrealized losses greater than one year			141,000,000	2,900,000
Aggregate loss of investments with unrealized losses greater than one year			1,200,000	300,000
Fair market value of investments with unrealized losses less than one year			1,209,900,000	730,100,000
Aggregate loss of investments with unrealized losses less than one year			2,200,000	2,500,000
Unrealized Gain (loss) on contracts			$ (2,900,000)	$ 8,000,000	2,500,000
Proceeds from sale of equity interest	$ 5,400,000	$ 34,200,000			$ 5,406,000
Accounts Receivable | Customer 1 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage			10.00%
Accounts Receivable | Customer 2 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage				10.00%
Equity and Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available for sale securities with out contractual maturity date			$ 23,400,000
Universal Robots
Financial Instruments and Fair Value [Line Items]
Maximum payment per earn-out			25,000,000
Foreign Exchange Contracts
Financial Instruments and Fair Value [Line Items]
Unrealized Gain (loss) on contracts			$ (100,000)	$ (100,000)

Schedule of Fair Value of Finan

Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	$ 1,473,905	$ 1,304,867
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	855,795	902,800
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	282,840	161,630
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	133,186	100,153
Certificates of Deposit and Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	167,342	82,133
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	10,726	39,252
Equity and Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	23,430	18,171
Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	586	728
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,903,748	1,612,751
Derivative assets	389	1
Total	1,904,137	1,612,752
Contingent consideration	45,102	38,332
Derivative liabilities	446	131
Total	45,548	38,463
Fair Value, Measurements, Recurring | Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	197,955	214,722
Fair Value, Measurements, Recurring | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	231,888	93,162
Fair Value, Measurements, Recurring | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	855,795	902,800
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	282,840	161,630
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	133,186	100,153
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	167,342	82,133
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	10,726	39,252
Fair Value, Measurements, Recurring | Equity and Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	23,430	18,171
Fair Value, Measurements, Recurring | Non-U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	586	728
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	427,720	270,351
Total	427,720	270,351
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	197,955	214,722
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	206,335	37,458
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Fair Value, Measurements, Recurring | Equity and Debt Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available for sale securities	23,430	18,171
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total	1,476,028	1,342,400
Derivative assets	389	1
Total	1,476,417	1,342,401
Derivative liabilities	446	131
Total	446	131
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	25,553	55,704
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	855,795	902,800
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	282,840	161,630
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	133,186	100,153
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	167,342	82,133
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	10,726	39,252
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	586	728
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	45,102	38,332
Total	$ 45,102	$ 38,332

Schedule of Reported Financial

Schedule of Reported Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	$ 1,904,137	$ 1,612,752
Liabilities	45,548	38,463
Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	446	131
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	429,843	307,884
Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	1,347,979	871,024
Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	125,926	433,843
Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	389	1
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	24,497	1,050
Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	20,605	37,282
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	427,720	270,351
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	404,290	252,180
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	23,430	18,171
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	1,476,417	1,342,401
Liabilities	446	131
Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	446	131
Significant Other Observable Inputs (Level 2) | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	25,553	55,704
Significant Other Observable Inputs (Level 2) | Marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	1,347,979	871,024
Significant Other Observable Inputs (Level 2) | Long-term marketable securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	102,496	415,672
Significant Other Observable Inputs (Level 2) | Prepayments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets	389	1
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	45,102	38,332
Significant Unobservable Inputs (Level 3) | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	24,497	1,050
Significant Unobservable Inputs (Level 3) | Long Term Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Liabilities	$ 20,605	$ 37,282

Schedule of Changes in Fair Val

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		$ 38,332		$ 37,436
Payments		(1,050)	[1]	(15,000)	[2]
Ending Balance		45,102		38,332
Avionics Interface Technologies, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value adjustment	[3]			550
Universal Robots
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value adjustment		$ 7,820	[4]	$ 15,346	[3]
[1]	During the year ended December 31, 2017, Teradyne paid $1.1 million of contingent consideration for the earn-out in connection with the acquisition of AIT.
[2]	During the year ended December 31, 2016, based on Universal Robots' calendar year 2015 EBITDA results, Teradyne paid $15 million or 100% of the eligible EBITDA contingent consideration amount.
[3]	During the year ended December 31, 2016, the fair value of contingent consideration for the earn-out in connection with the acquisition of Universal Robots was increased by $15.3 million primarily due to an increase in forecasted revenues and a decrease in the discount rate. During the year ended 2016, the fair value of contingent consideration for the earn-out in connection with the acquisition of Avionics Interface Technologies, LLC ("AIT") was increased by $0.6 million due to an increase in forecasted revenues.
[4]	During the year ended December 31, 2017, the fair value of contingent consideration for the earn-out in connection with the acquisition of Universal Robots was increased by $7.8 million primarily due to an increase in forecasted revenues and decrease in discount rate.

Schedule of Changes in Fair V68

Schedule of Changes in Fair Value of Level 3 Contingent Consideration (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Apr. 03, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration									$ 1,050	$ 11,697
Increase (decrease) in contingent consideration									7,820	15,896	$ 2,489
Avionics Interface Technologies, LLC
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration									1,100
Increase (decrease) in contingent consideration										600	(1,300)
Universal Robots
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payments of contingent consideration								$ 15,000		$ 15,000
EBITDA contingent consideration amount, percentage					100.00%			100.00%		100.00%
Increase (decrease) in contingent consideration	$ 6,000	$ (300)	$ 1,500	$ 600	$ 5,400	$ 8,000	$ 1,200		$ 7,800	$ 15,300	$ 5,300

Quantitative Information Associ

Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Jun. 11, 2015
Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration			$ 31,600
Significant Unobservable Inputs (Level 3) | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration	[1]	$ 24,497
Monte Carlo Simulation | Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		$ 20,605
Monte Carlo Simulation | Revenue for the period July 1, 2015-December 31, 2017 | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Target achievement, volatility		11.20%
Discount Rate		3.30%
[1]	Contingent consideration of $24.5 million is expected to be paid in March 2018.

Quantitative Information Asso70

Quantitative Information Associated With Fair Value Measurement of Level 3 Financial Instrument (Parenthetical) (Detail) $ in Millions	1 Months Ended
	Mar. 31, 2018USD ($)
Scenario, Forecast | Universal Robots
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Payment for contingent consideration	$ 24.5

Schedule of Carrying Amounts an

Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Marketable securities		$ 1,473,905	$ 1,304,867
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		429,843	307,884
Marketable securities		1,473,905	1,304,867
Derivative assets		389	1
Contingent consideration		45,102	38,332
Derivative liabilities		446	131
Convertible debt	[1]	659,525	486,754
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and cash equivalents		429,843	307,884
Marketable securities		1,473,905	1,304,867
Derivative assets		389	1
Contingent consideration		45,102	38,332
Derivative liabilities		446	131
Convertible debt	[1]	$ 365,987	$ 352,669
[1]	The carrying value represents the bifurcated debt component only, while the fair value is based on quoted market prices for the convertible note which includes the equity conversion features.

Schedule of Available for Sale

Schedule of Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 1,470,729	$ 1,304,711
Available-for-sale marketable securities, Unrealized Gain	6,582	2,977
Available-for-sale marketable securities, Unrealized (Loss)	(3,406)	(2,821)
Available-for-sale marketable securities, Fair Market Value	1,473,905	1,304,867
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,350,896	732,979
U.S. Treasury Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	858,258	904,737
Available-for-sale marketable securities, Unrealized Gain	72	97
Available-for-sale marketable securities, Unrealized (Loss)	(2,535)	(2,034)
Available-for-sale marketable securities, Fair Market Value	855,795	902,800
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	850,163	572,284
Corporate Debt Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	131,179	99,708
Available-for-sale marketable securities, Unrealized Gain	2,380	1,065
Available-for-sale marketable securities, Unrealized (Loss)	(373)	(620)
Available-for-sale marketable securities, Fair Market Value	133,186	100,153
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	91,010	53,642
U.S. Government Agency Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	10,775	39,264
Available-for-sale marketable securities, Unrealized Gain		7
Available-for-sale marketable securities, Unrealized (Loss)	(49)	(19)
Available-for-sale marketable securities, Fair Market Value	10,726	39,252
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	10,726	13,461
Certificates of Deposit and Time Deposits
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	167,523	82,080
Available-for-sale marketable securities, Unrealized Gain	6	54
Available-for-sale marketable securities, Unrealized (Loss)	(187)	(1)
Available-for-sale marketable securities, Fair Market Value	167,342	82,133
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	138,340	7,760
Commercial Paper
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	283,009	161,672
Available-for-sale marketable securities, Unrealized Gain	18	24
Available-for-sale marketable securities, Unrealized (Loss)	(187)	(66)
Available-for-sale marketable securities, Fair Market Value	282,840	161,630
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	258,933	84,034
Equity and Debt Mutual Funds
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	19,403	16,505
Available-for-sale marketable securities, Unrealized Gain	4,102	1,724
Available-for-sale marketable securities, Unrealized (Loss)	(75)	(58)
Available-for-sale marketable securities, Fair Market Value	23,430	18,171
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,723	1,661
Non-U.S. Government Securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	582	745
Available-for-sale marketable securities, Unrealized Gain	4	6
Available-for-sale marketable securities, Unrealized (Loss)		(23)
Available-for-sale marketable securities, Fair Market Value	$ 586	728
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses		$ 137

Schedule of Reported Available

Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 1,470,729	$ 1,304,711
Available-for-sale marketable securities, Unrealized Gain	6,582	2,977
Available-for-sale marketable securities, Unrealized (Loss)	(3,406)	(2,821)
Available-for-sale marketable securities, Fair Market Value	1,473,905	1,304,867
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,350,896	732,979
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	1,349,970	871,321
Available-for-sale marketable securities, Unrealized Gain	38	134
Available-for-sale marketable securities, Unrealized (Loss)	(2,029)	(431)
Available-for-sale marketable securities, Fair Market Value	1,347,979	871,024
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	1,288,844	423,128
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	120,759	433,390
Available-for-sale marketable securities, Unrealized Gain	6,544	2,843
Available-for-sale marketable securities, Unrealized (Loss)	(1,377)	(2,390)
Available-for-sale marketable securities, Fair Market Value	125,926	433,843
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 62,052	$ 309,851

Contractual Maturities of Inves

Contractual Maturities of Investments Held (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities
Due within one year, cost	$ 1,349,970
Due after 1 year through 5 years, cost	48,796
Due after 5 years through 10 years, cost	13,916
Due after 10 years, cost	38,644
Total, cost	1,451,326
Due within one year, fair value	1,347,979
Due after 1 year through 5 years, fair value	48,599
Due after 5 years through 10 years, fair value	13,489
Due after 10 years, fair value	40,408
Total, fair value	$ 1,450,475

Non-Financial Assets Measured a

Non-Financial Assets Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
		Dec. 31, 2016	Jul. 03, 2016		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, impairment loss		$ 0	$ 254,946	[1],[2]	$ 0	$ 254,946
Definite lived intangible assets, impairment loss			83,339	[1],[2]		$ 83,339
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, fair value	[3]		7,976
Definite lived intangible assets, fair value	[4]		5,750
Total			13,726
Goodwill, impairment loss	[3]		254,946
Definite lived intangible assets, impairment loss	[4]		83,339
Asset Impairment Charges, Total			338,285
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, fair value	[3]		7,976
Definite lived intangible assets, fair value	[4]		5,750
Total			$ 13,726
[1]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	In accordance with the provisions of ASC 350-20, "Goodwill", goodwill in the Wireless Test reporting unit with a carrying amount of $262.9 million was written down in the second quarter of 2016 to its implied fair value of $8.0 million, resulting in an impairment charge of $254.9 million. See Note J: "Goodwill and Intangible Assets" regarding goodwill impairment.
[4]	In accordance with the provisions of ASC 360-10, "Property, Plant and Equipment", definite lived intangible assets in the Wireless Test reporting unit with a carrying amount of $89.2 million were written down in the second quarter of 2016 to their implied fair value of $5.8 million, resulting in an impairment charge of $83.3 million. See Note J: "Goodwill and Intangible Assets" regarding definite lived intangible assets impairment.

Non-Financial Assets Measured76

Non-Financial Assets Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
		Dec. 31, 2016	Jul. 03, 2016		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, carrying value		$ 985,909			$ 1,014,577	$ 985,909	$ 996,033
Goodwill, impairment loss		0	$ 254,946	[1],[2]	0	254,946
Definite lived intangible assets, carrying value		414,038			414,038	414,038
Definite lived intangible assets, impairment loss			83,339	[1],[2]		83,339
Wireless Test
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, carrying value		$ 361,819			$ 361,819	361,819	$ 361,819
Goodwill, impairment loss			254,900			254,946
Definite lived intangible assets, impairment loss			83,300			$ 83,339
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, fair value	[3]		7,976
Goodwill, impairment loss	[3]		254,946
Definite lived intangible assets, fair value	[4]		5,750
Definite lived intangible assets, impairment loss	[4]		83,339
Fair Value, Measurements, Nonrecurring | Wireless Test
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, carrying value			262,900
Goodwill, fair value			8,000
Goodwill, impairment loss			254,900
Definite lived intangible assets, carrying value			89,200
Definite lived intangible assets, fair value			5,800
Definite lived intangible assets, impairment loss			$ 83,300
[1]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	In accordance with the provisions of ASC 350-20, "Goodwill", goodwill in the Wireless Test reporting unit with a carrying amount of $262.9 million was written down in the second quarter of 2016 to its implied fair value of $8.0 million, resulting in an impairment charge of $254.9 million. See Note J: "Goodwill and Intangible Assets" regarding goodwill impairment.
[4]	In accordance with the provisions of ASC 360-10, "Property, Plant and Equipment", definite lived intangible assets in the Wireless Test reporting unit with a carrying amount of $89.2 million were written down in the second quarter of 2016 to their implied fair value of $5.8 million, resulting in an impairment charge of $83.3 million. See Note J: "Goodwill and Intangible Assets" regarding definite lived intangible assets impairment.

Schedule of Notional Amount of

Schedule of Notional Amount of Derivatives (Detail) - Foreign Exchange Contracts - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	$ 5	$ 14.5
Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(55.9)	(34.7)
Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	60.9	49.2
Japanese Yen
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(35.7)	(17.7)
Japanese Yen | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(35.7)	(17.7)
Taiwan Dollar
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(9.9)	(6.9)
Taiwan Dollar | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(9.9)	(6.9)
Korean Won
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(8.9)	(8.8)
Korean Won | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(8.9)	(8.8)
British Pound Sterling
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(1.4)	(1.3)
British Pound Sterling | Buy Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Liability, Notional amounts	(1.4)	(1.3)
Singapore Dollar
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	33.5	24
Singapore Dollar | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	33.5	24
Euro
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	27.4	25.2
Euro | Sell Position
Intercompany Foreign Currency Balance [Line Items]
Derivative Asset, Notional amounts	$ 27.4	$ 25.2

Schedule of Derivative Instrume

Schedule of Derivative Instruments in Statement of Financial Position at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net	$ (57)	$ (130)
Not Designated as Hedging Instrument | Foreign Exchange Contracts | Prepayments
Derivatives, Fair Value [Line Items]
Derivative assets	389	1
Not Designated as Hedging Instrument | Foreign Exchange Contracts | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (446)	$ (131)

Schedule of Effect of Derivativ

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
(Gains) losses on derivatives recognized in statements of operations	$ (1,133)	$ 8,671	$ 3,047

Schedule of Effect of Derivat80

Schedule of Effect of Derivative Instruments in Statement of Operations Recognized (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on foreign currency transactions	$ (2.9)	$ 8	$ 2.5

Debt - Additional Information (

Debt - Additional Information (Detail) $ / shares in Units, shares in Millions	Dec. 12, 2016USD ($)d$ / sharesshares	Apr. 27, 2015USD ($)	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Debt Instrument
Debt instrument, net proceeds after issuance costs				$ 450,800,000
Repurchase of common stock			$ 200,304,000	$ 146,331,000	$ 299,949,000
Repurchase of stock, shares | shares				6.8	15.6
Term of loan, years		5 years
Pledge percentage of capital stock		65.00%
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Aggregate principal amount	$ 460,000,000		$ 460,000,000	$ 460,000,000
Debt instrument, interest rate, stated percentage	1.25%
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
Repurchase of common stock	$ 50,100,000
Repurchase of stock, shares | shares	2
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	$ 31.80		$ 31.80
Shares that would be issued upon conversion | shares			14.5
Strike price per share of warrant | $ / shares			$ 39.91
Debt instrument, convertible, carrying amount of equity component	$ 100,800,000		$ 100,800,000
Debt instrument, effective annual interest rate			5.00%
Financing cost	$ 7,200,000		$ 6,300,000
Debt issuance costs, amortization period			7 years
Unamortized discount			$ 94,000,000
Debt Instrument, convertible, remaining discount amortization period			6 years
Value of notes converted			$ 605,700,000
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option one
Debt Instrument
Trading days measurement period | d	20
Consecutive trading days measurement period | d	30
Percentage of conversion price	130.00%
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option two
Debt Instrument
Trading days measurement period | d	5
Consecutive trading days measurement period | d	5
Percentage of closing sale price of common stock and conversion rate product	98.00%
Maximum
Debt Instrument
Aggregate principal amount		$ 150,000,000
Commitment fee percentage of unused portion of credit facility		0.35%
Minimum
Debt Instrument
Commitment fee percentage of unused portion of credit facility		0.125%
Base Rate | Maximum
Debt Instrument
Debt instrument, basis spread on variable rate		1.00%
Base Rate | Minimum
Debt Instrument
Debt instrument, basis spread on variable rate		0.00%
London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument
Debt instrument, basis spread on variable rate		2.00%
London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument
Debt instrument, basis spread on variable rate		1.00%
Revolving Credit Facility
Debt Instrument
Financing cost			$ 2,300,000
Financing cost, amortization term			5 years
Revolving Credit Facility | Maximum
Debt Instrument
Credit facility, borrowing capacity		$ 350,000,000

Components of Convertible Senio

Components of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 12, 2016
Debt Instrument
Net Carrying amount of convertible debt	$ 365,987	$ 352,669
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Debt Principal	460,000	460,000	$ 460,000
Unamortized discount	94,013	107,331
Net Carrying amount of convertible debt	$ 365,987	$ 352,669

Interest Expense on Convertible

Interest Expense on Convertible Senior Notes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument
Contractual interest expense on the coupon	$ 5,734	$ 303
Amortization of the discount component and debt issue fees recognized as interest expense	13,318	688
Total interest expense on the convertible debt	$ 19,052	$ 991

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 1,828,659	$ 1,965,786	$ 2,078,980
Other comprehensive (loss) income before reclassifications, net of tax	39,703	(11,066)
Amounts reclassified from accumulated other comprehensive income, net of tax	(713)	(1,004)
Other comprehensive income (loss)	38,990	(12,070)	(12,833)
Balance	1,953,646	1,828,659	1,965,786
Foreign currency translation reclassification adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(21,921)	(8,759)
Other comprehensive (loss) income before reclassifications, net of tax	37,840	(13,162)
Other comprehensive income (loss)	37,840	(13,162)
Balance	15,919	(21,921)	(8,759)
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(60)	(1,414)
Other comprehensive (loss) income before reclassifications, net of tax	1,863	2,037
Amounts reclassified from accumulated other comprehensive income, net of tax	(441)	(683)
Other comprehensive income (loss)	1,422	1,354
Balance	1,362	(60)	(1,414)
Amortization of prior service credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	1,767	2,029
Other comprehensive (loss) income before reclassifications, net of tax		59
Amounts reclassified from accumulated other comprehensive income, net of tax	(272)	(321)	(295)
Other comprehensive income (loss)	(272)	(262)
Balance	1,495	1,767	2,029
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(20,214)	(8,144)	4,689
Amounts reclassified from accumulated other comprehensive income, net of tax	(713)	(1,004)	(999)
Balance	$ 18,776	$ (20,214)	$ (8,144)

Changes in Accumulated Other 85

Changes in Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income, tax	$ (451)	$ (445)	$ (559)
Foreign currency translation adjustments, tax	0	0	0
Unrealized gains on marketable securities, tax	1,815	209	(459)
Retirement plans prior service benefit, tax	(932)	(778)	(622)
Foreign currency translation reclassification adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income before reclassifications, tax	0	0
Amounts reclassified from accumulated other comprehensive income, tax	0	0
Other comprehensive (loss) income, tax	0	0
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income before reclassifications, tax	1,903	923
Amounts reclassified from accumulated other comprehensive income, tax	(297)	(255)	(390)
Other comprehensive (loss) income, tax	1,606	668
Amortization of prior service credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income before reclassifications, tax	0	34
Amounts reclassified from accumulated other comprehensive income, tax	(154)	(190)	$ (169)
Other comprehensive (loss) income, tax	$ (154)	$ (156)

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Detail) - USD ($) $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

[1],[2]

Oct. 01, 2017

[3]

Jul. 02, 2017

[2],[4]

Apr. 02, 2017

[5]

Dec. 31, 2016

[6],[7]

Oct. 02, 2016

[7],[8]

Jul. 03, 2016

[7],[9]

Apr. 03, 2016

[7],[10]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Interest income

$ (6,476)

$ (4,517)

$ (3,292)

$ (3,520)

$ (3,095)

$ (2,892)

$ (1,666)

$ (1,642)

$ (17,805)

$ (9,296)

$ (7,214)

Reclassifications, net of tax

713

1,004

Unrealized Gains (Losses) on Marketable Securities

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Reclassifications, net of tax

441

683

Amortization of prior service credit

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Reclassifications, net of tax

272

321

295

Accumulated Other Comprehensive Income (Loss)

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Reclassifications, net of tax

713

1,004

999

Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains (Losses) on Marketable Securities

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Interest income

$ 441

$ 683

$ 704

[1]

Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.

[2]

Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[3]

Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.

[4]

Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.

[5]

Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.

[6]

Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[7]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[8]

Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[9]

Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.

[10]

Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Reclassifications Out of Accu87

Reclassifications Out of Accumulated Other Comprehensive Income to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 451	$ 445	$ 559
Unrealized Gains (Losses) on Marketable Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	297	255	390
Amortization of prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, tax	$ 154	$ 190	$ 169

Goodwill and Intangible Asset88

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

3 Months Ended

12 Months Ended

Dec. 31, 2017

Oct. 01, 2017

[5]

Jul. 02, 2017

[4],[6]

Apr. 02, 2017

[7]

Dec. 31, 2016

Oct. 02, 2016

[2],[9]

Jul. 03, 2016

Apr. 03, 2016

[2],[10]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Line Items]

Goodwill

$ 252,011

$ 223,343

$ 252,011

$ 223,343

$ 488,413

Goodwill impairment

0

$ 254,946

[1],[2]

0

254,946

Acquired intangible assets impairment

83,339

[1],[2]

83,339

Intangible assets remaining balance

79,088

100,401

79,088

100,401

Acquired intangible assets amortization

7,384

[3],[4]

$ 7,028

$ 8,166

$ 7,952

7,923

[2],[8]

$ 8,487

$ 16,244

[1],[2]

$ 19,994

30,530

52,648

69,031

Wireless Test

Goodwill and Intangible Assets Disclosure [Line Items]

Employee reduction, percentage

11.00%

Goodwill

7,976

$ 7,976

$ 8,000

7,976

7,976

$ 262,922

Goodwill impairment

254,900

254,946

Acquired intangible assets impairment

$ 83,300

$ 83,339

Intangible assets remaining balance

$ 3,600

$ 3,600

Wireless Test | Sales Revenue, Segment | Customer Concentration Risk | Minimum

Goodwill and Intangible Assets Disclosure [Line Items]

Concentration risk, percentage

51.00%

Wireless Test | Sales Revenue, Segment | Customer Concentration Risk | Maximum

Goodwill and Intangible Assets Disclosure [Line Items]

Concentration risk, percentage

73.00%

[1]

Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.

[2]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[3]

Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.

[4]

Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[5]

Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.

[6]

Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.

[7]

Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.

[8]

Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[9]

Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[10]

Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Changes in Carrying Amount of G

Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Jul. 03, 2016		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Foreign currency translation adjustment				$ 28,668	$ (10,124)
Goodwill impairment losses	$ 0	$ (254,946)	[1],[2]	0	(254,946)
Goodwill	985,909			1,014,577	985,909	$ 996,033
Accumulated impairment losses	(762,566)			(762,566)	(762,566)	(507,620)
Goodwill	223,343			252,011	223,343	488,413
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment				28,668	(10,124)
Goodwill	204,851			233,519	204,851	214,975
Goodwill	204,851			233,519	204,851	214,975
System Test
Goodwill [Line Items]
Goodwill	158,699			158,699	158,699	158,699
Accumulated impairment losses	(148,183)			(148,183)	(148,183)	(148,183)
Goodwill	10,516			10,516	10,516	10,516
Wireless Test
Goodwill [Line Items]
Goodwill impairment losses		(254,900)			(254,946)
Goodwill	361,819			361,819	361,819	361,819
Accumulated impairment losses	(353,843)			(353,843)	(353,843)	(98,897)
Goodwill	7,976	$ 8,000		7,976	7,976	262,922
Semiconductor Test
Goodwill [Line Items]
Goodwill	260,540			260,540	260,540	260,540
Accumulated impairment losses	$ (260,540)			$ (260,540)	$ (260,540)	$ (260,540)
[1]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[2]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

Schedule of Amortizable Intangi

Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 414,038	$ 414,038
Accumulated Amortization	(337,155)	(306,698)
Foreign Currency Translation Adjustment	2,205	(6,939)
Net Carrying Amount	79,088	100,401
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	270,877	270,877
Accumulated Amortization	(226,190)	(206,376)
Foreign Currency Translation Adjustment	1,618	(5,093)
Net Carrying Amount	46,305	59,408
Customer Relationships
Finite-Lived Intangible Assets
Gross Carrying Amount	92,741	92,741
Accumulated Amortization	(83,585)	(76,707)
Foreign Currency Translation Adjustment	171	(538)
Net Carrying Amount	9,327	15,496
Trademarks and tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	50,100	50,100
Accumulated Amortization	(27,120)	(23,435)
Foreign Currency Translation Adjustment	416	(1,308)
Net Carrying Amount	23,396	25,357
Non-compete Agreements
Finite-Lived Intangible Assets
Gross Carrying Amount	320	320
Accumulated Amortization	(260)	(180)
Net Carrying Amount	$ 60	$ 140

Schedule of Estimated Intangibl

Schedule of Estimated Intangible Asset Amortization Expense (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets
2,018	$ 29,496
2,019	25,533
2,020	11,249
2,021	3,732
2,022	2,927
Thereafter	$ 6,151

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	$ 280.4
Purchase commitments less than one year	271.1
Rental expense under lease commitments	$ 18.9	$ 18.8	$ 15.9
Warranty period	1 year
Product warranty accrual	$ 8.2	7.2
Revenue deferrals related to extended warranties	$ 24.4	$ 28.2

Non Cancelable Operating Lease

Non Cancelable Operating Lease Commitments (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Line Items]
2,018	$ 17,560
2,019	14,355
2,020	11,851
2,021	9,201
2,022	7,331
Beyond 2,023	7,425
Total	$ 67,723

Computation of Basic and Dilute

Computation of Basic and Diluted Net (Loss) Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2017	[1],[2]	Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016	[6],[7]	Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Income Loss Per Common Share
Net income (loss) for basic and diluted net income per share		$ (105,923)		$ 103,420		$ 174,976		$ 85,221		$ 66,345		$ 63,794		$ (223,546)		$ 49,986		$ 257,692	$ (43,421)	$ 206,477
Weighted average common shares-basic																		198,069	202,578	211,544
Incremental shares from assumed conversion of convertible notes	[11]																	1,298
Convertible note hedge warrant shares	[12]																	112
Employee stock purchase rights																		27		41
Dilutive potential common shares																		3,572		1,777
Weighted average common shares-diluted																		201,641	202,578	213,321
Net income (loss) per common share-basic		$ (0.54)		$ 0.52		$ 0.88		$ 0.43		$ 0.33		$ 0.32		$ (1.10)		$ 0.24		$ 1.30	$ (0.21)	$ 0.98
Net income (loss) per common share-diluted		$ (0.54)		$ 0.52		$ 0.87		$ 0.42		$ 0.33		$ 0.31		$ (1.10)		$ 0.24		$ 1.28	$ (0.21)	$ 0.97
Restricted Stock Units
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																		1,800		1,130
Stock Options
Net Income Loss Per Common Share
Incremental shares attributable to share based payment arrangements																		335		606
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[11]	Incremental shares from the assumed conversion of the convertible notes was calculated using the difference between the average Teradyne stock price for the period and the conversion price of $31.80, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the convertible debt, was divided by the average Teradyne stock price for the period.
[12]	Convertible notes hedge warrant shares were calculated using the difference between the average Teradyne stock price for the period and the warrant price of $39.91, multiplied by 14.5 million shares. The result of this calculation, representing the total intrinsic value of the warrant, was divided by the average Teradyne stock price for the period. Teradyne's call option on its common stock (convertible note hedge transaction) was excluded from the calculation of diluted shares because the effect was anti-dilutive.

Computation of Basic and Dilu95

Computation of Basic and Diluted Net (Loss) Income Per Common Share (Parenthetical) (Detail) shares in Millions	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 31.80
Shares that would be issued upon conversion | shares	14.5
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 39.91
Shares that would be issued upon conversion | shares	14.5

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share - Additional Information (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Net Income Loss Per Common Share
Exercise of stock options	0.1	0.2

Restructuring and Other - Addit

Restructuring and Other - Additional Information (Detail) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2017USD ($)	Oct. 01, 2017USD ($)	Jul. 02, 2017USD ($)	Apr. 02, 2017USD ($)	Dec. 31, 2016USD ($)	Oct. 02, 2016USD ($)	Apr. 03, 2016USD ($)	Dec. 31, 2017USD ($)Employee	Dec. 31, 2016USD ($)Employee	Dec. 31, 2015USD ($)Employee
Restructuring Cost and Reserve
Contingent consideration adjustment								$ 7,820	$ 15,896	$ 2,489
Severance benefit and charges	$ 1,800	$ 600	$ 800	$ 600				$ 1,400
Lease termination period								2017-09
Property, Plant and Equipment
Restructuring Cost and Reserve
Impairment of fixed assets and other expenses									4,200
Wireless Test
Restructuring Cost and Reserve
Lease impairment								$ 1,000
Semiconductor Test | Property, Plant and Equipment
Restructuring Cost and Reserve
Impairment of fixed assets and other expenses								1,100
Impairment of fixed assets and expenses related to the Japan earthquake
Restructuring Cost and Reserve
Property insurance, recovery		5,100						5,100	5,100
Impairment of fixed assets and expenses related to the Japan earthquake | Earthquake Related Expenses
Restructuring Cost and Reserve
Impairment of fixed assets and other expenses		800						800	900
Universal Robots
Restructuring Cost and Reserve
Contingent consideration adjustment	$ 6,000	$ (300)	$ 1,500	$ 600	$ 5,400	$ 8,000	$ 1,200	7,800	15,300	5,300
Acquisition related costs										1,000
Avionics Interface Technologies, LLC
Restructuring Cost and Reserve
Contingent consideration adjustment									600	(1,300)
ZTEC Corporation and Avionics Interface Technologies LLC
Restructuring Cost and Reserve
Contingent consideration adjustment										(2,900)
ZTEC Instruments, Inc.
Restructuring Cost and Reserve
Contingent consideration adjustment										(1,600)
Semiconductor Test and Wireless Test
Restructuring Cost and Reserve
Severance benefit and charges									$ 6,000
Reduction in employees headcount | Employee									146
Semiconductor Test and Wireless Test | Wireless Test
Restructuring Cost and Reserve
Reduction in employees headcount | Employee									102
Semiconductor Test and Wireless Test | Semiconductor Test
Restructuring Cost and Reserve
Reduction in employees headcount | Employee									44
System Test and Semiconductor Test
Restructuring Cost and Reserve
Severance benefit and charges										$ 1,500
Reduction in employees headcount | Employee										23
Semiconductor Test, Industrial Automation and Corporate
Restructuring Cost and Reserve
Severance benefit and charges								$ 3,800
Reduction in employees headcount | Employee								91
Semiconductor Test, Industrial Automation and Corporate | Semiconductor Test
Restructuring Cost and Reserve
Reduction in employees headcount | Employee								75
Semiconductor Test, Industrial Automation and Corporate | Industrial Automation
Restructuring Cost and Reserve
Reduction in employees headcount | Employee								8
Semiconductor Test, Industrial Automation and Corporate | Corporate
Restructuring Cost and Reserve
Reduction in employees headcount | Employee								8

Schedule of Defined Benefit Pen

Schedule of Defined Benefit Pension and Postretirement Benefit Plan Assets and Obligation (Detail) - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2017	Jul. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Actuarial loss	$ (3,800)	$ (2,500)	$ (2,000)	$ 700	$ (700)	$ (1,200)
Ending Balance	325,800						$ 325,800
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year						351,117	353,616	$ 351,117
Service cost							2,239	2,302	$ 2,462
Interest cost							13,151	13,630	13,142
Actuarial loss							12,702	6,053
Benefits paid							(18,682)	(19,486)
Projected benefit obligation, End of year	363,026		353,616				363,026	353,616	351,117
Beginning Balance						298,404	307,304	298,404
Company contributions							4,462	4,489
Actual return on plan assets							31,422	23,897
Benefits paid							(18,682)	(19,486)
Ending Balance	324,506		307,304				324,506	307,304	298,404
Funded status	(38,520)		(46,312)				(38,520)	(46,312)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year						62,290	60,738	62,290
Service cost							818	761	1,006
Interest cost							852	1,185	1,444
Actuarial loss							262	5,621
Benefits paid							(994)	(1,385)
Settlements							(28,560)
Expenses paid							(40)	(609)
Non-U.S. currency movement							6,277	(7,125)
Projected benefit obligation, End of year	39,353		60,738				39,353	60,738	62,290
Beginning Balance						28,141	27,571	28,141
Company contributions							883	867
Actual return on plan assets							737	5,142
Benefits paid							(994)	(1,148)
Settlements							(28,560)
Expenses paid							(40)	(609)
Non-U.S. currency movement							1,710	(4,822)
Ending Balance	1,307		27,571				1,307	27,571	28,141
Funded status	(38,046)		(33,167)				(38,046)	(33,167)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Projected benefit obligation, Beginning of year						$ 6,030	5,510	6,030
Service cost							34	37	48
Interest cost							201	218	237
Actuarial loss							398	5
Special termination benefits							591
Benefits paid							(557)	(687)
Plan amendments								(93)
Projected benefit obligation, End of year	6,177		5,510				6,177	5,510	$ 6,030
Company contributions							557	687
Benefits paid							(557)	(687)
Funded status	$ (6,177)		$ (5,510)				$ (6,177)	$ (5,510)

Schedule of Amounts Recorded wi

Schedule of Amounts Recorded within Statements of Financial Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure
Retirement plans assets	$ 17,491	$ 7,712
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Retirement plans assets	17,491	7,712
Accrued employees' compensation and withholdings	(2,524)	(2,591)
Retirement plans liabilities	(53,487)	(51,433)
Funded status	(38,520)	(46,312)
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Accrued employees' compensation and withholdings	(863)	(772)
Retirement plans liabilities	(37,183)	(32,395)
Funded status	(38,046)	(33,167)
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Accrued employees' compensation and withholdings	(591)	(571)
Retirement plans liabilities	(5,586)	(4,939)
Funded status	$ (6,177)	$ (5,510)

Schedule of Amounts Recognized

Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Deferred taxes	$ (12,881)	$ (9,398)	$ (10,235)
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Prior service cost, before tax	58	127
Deferred taxes	539	514
Total recognized in other comprehensive income, net of tax	597	641
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Prior service cost, before tax	(622)	(1,118)
Deferred taxes	(1,472)	(1,292)
Total recognized in other comprehensive income, net of tax	$ (2,094)	$ (2,410)

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Accumulated other comprehensive income (loss), prior service cost expected to be recognized in 2018	$ 100
Fair value of pension plans assets totaled	325,800
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Accumulated other comprehensive income (loss), prior service cost expected to be recognized in 2018	$ (100)
Discount rate utilized to determine future pension obligations	3.40%	3.90%	3.90%
Contribution to defined benefit pension plans	$ 557	$ 687
United States Plans
Defined Benefit Plan Disclosure
Percentage of expected return on plan assets assumption	4.00%
Discount rate utilized to determine future pension obligations	3.40%	3.90%
Fair value of pension plans assets totaled	$ 324,500
Contribution to defined benefit pension plans	1,900	$ 1,900
Contribution to defined benefit pension plans in 2018	1,900
Taiwan Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Fair value of pension plans assets totaled	1,300
U.S. Supplemental Executive Defined Benefit Pension Plan
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	2,600	2,600
Contribution to defined benefit pension plans in 2018	2,500
Non-United States Subsidiaries
Defined Benefit Plan Disclosure
Contribution to defined benefit pension plans	900	900
Contribution to defined benefit pension plans in 2018	900
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Accumulated benefit obligation for defined benefit pension plans	$ 354,300	$ 342,900
Percentage of expected return on plan assets assumption	4.00%	4.80%	4.80%
Discount rate utilized to determine future pension obligations	3.40%	3.90%
Fair value of pension plans assets totaled	$ 324,506	$ 307,304	$ 298,404
Contribution to defined benefit pension plans	4,462	4,489
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Accumulated benefit obligation for defined benefit pension plans	$ 34,700	$ 56,600
Percentage of expected return on plan assets assumption	2.00%	2.00%	2.60%
Discount rate utilized to determine future pension obligations	1.80%	1.80%
Fair value of pension plans assets totaled	$ 1,307	$ 27,571	$ 28,141
Contribution to defined benefit pension plans	$ 883	$ 867

Schedule of Pension Plans with

Schedule of Pension Plans with Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation	$ 56	$ 54
Accumulated benefit obligation	51.6	48
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Projected benefit obligation	39.4	34.3
Accumulated benefit obligation	34.7	30.1
Fair value of plan assets	$ 1.3	$ 1.1

Schedule of Net Periodic Pensio

Schedule of Net Periodic Pension and Postretirement (income) Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Net actuarial (gain) loss	$ (6,624)	$ (3,203)	$ 17,732
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	2,239	2,302	2,462
Interest cost	13,151	13,630	13,142
Expected return on plan assets	(12,008)	(13,830)	(14,517)
Amortization of prior service cost	70	96	134
Net actuarial (gain) loss	(6,712)	(4,013)	10,596
Total net periodic pension (income) cost	(3,260)	(1,815)	11,817
Prior service cost	(70)	(96)	(134)
Total recognized in other comprehensive income	(70)	(96)	(134)
Total recognized in net periodic pension (income) cost and other comprehensive income	(3,330)	(1,911)	11,683
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Service cost	818	761	1,006
Interest cost	852	1,185	1,444
Expected return on plan assets	(165)	(443)	(781)
Net actuarial (gain) loss	(310)	815	8,415
Curtailment			(634)
Total net periodic pension (income) cost	1,195	2,318	9,450
Total recognized in net periodic pension (income) cost and other comprehensive income	1,195	2,318	9,450
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Service cost	34	37	48
Interest cost	201	218	237
Amortization of prior service cost	(496)	(607)	(598)
Net actuarial (gain) loss	398	5	(648)
Special termination benefits	591
Total net periodic pension (income) cost	728	(347)	(961)
Prior service cost		(93)
Prior service credit	496	607	598
Total recognized in other comprehensive income	496	514	598
Total recognized in net periodic pension (income) cost and other comprehensive income	$ 1,224	$ 167	$ (363)

Schedule of Weighted Average -

Schedule of Weighted Average - Assumptions to Determine Net Periodic Pension Cost (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	3.90%	4.00%	3.70%
Expected return on plan assets	4.00%	4.80%	4.80%
Salary progression rate	2.60%	2.70%	2.90%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	1.80%	2.30%	2.60%
Expected return on plan assets	2.00%	2.00%	2.60%
Salary progression rate	2.70%	3.20%	3.20%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.90%	3.90%	3.50%
Initial health care cost trend rate	7.30%	7.50%	7.50%
Ultimate health care cost trend rate	5.00%	5.00%	5.00%
Year in which ultimate health care cost trend rate is reached	2,023	2,023	2,022

Schedule of Weighted Average As

Schedule of Weighted Average Assumptions to Determine Pension Obligations (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	3.40%	3.90%
Salary progression rate	2.30%	2.60%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	1.80%	1.80%
Salary progression rate	2.70%	2.70%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.40%	3.90%	3.90%
Initial medical trend	7.90%	7.30%	7.50%
Ultimate health care trend	5.00%	5.00%	5.00%
Medical cost trend rate decrease to ultimate rate in year	2,026	2,023	2,023

Schedule of Weighted Average Pe

Schedule of Weighted Average Pension Assets Allocations by Category (Detail)	Dec. 31, 2017	Dec. 31, 2016
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
United States Pension Plans, Defined Benefit | Fixed income securities
Defined Benefit Plan Disclosure
Total	88.10%	88.10%
United States Pension Plans, Defined Benefit | Equity securities
Defined Benefit Plan Disclosure
Total	9.90%	9.90%
United States Pension Plans, Defined Benefit | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	2.00%	2.00%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	100.00%	100.00%
Foreign Pension Plans, Defined Benefit | Other than Securities Investment
Defined Benefit Plan Disclosure
Total	100.00%	100.00%

Schedule of Target Assets Alloc

Schedule of Target Assets Allocation (Detail)	Dec. 31, 2017
Bloomberg Barclays Corporate or Better Index | U.S. corporate fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	76.00%
MSCI World Minimum Volatility Index | Global equity Securities
Defined Benefit Plan Disclosure
Target assets allocation percentage	10.00%
Bloomberg Barclays Capital Long Government Credit Index | U.S. government fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	8.00%
Bloomberg Barclays Corporate High Yield Issuer Cap Index | High yield fixed income
Defined Benefit Plan Disclosure
Target assets allocation percentage	5.00%
Citi Group Three Month Treasury Bill Index | Cash
Defined Benefit Plan Disclosure
Target assets allocation percentage	1.00%

Schedule of Fair Value of Pensi

Schedule of Fair Value of Pensions Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Total	$ 325,800
Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	3,166	$ 29,456	$ 29,392
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	324,506	307,304	298,404
United States Pension Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	3,217	3,023
United States Pension Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	318,123	301,210
United States Pension Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	3,166	3,071
United States Pension Plans, Defined Benefit | Corporate Debt Securities
Defined Benefit Plan Disclosure
Total	260,294	246,528
United States Pension Plans, Defined Benefit | Corporate Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	260,294	246,528
United States Pension Plans, Defined Benefit | US Government Debt Securities
Defined Benefit Plan Disclosure
Total	25,709	24,322
United States Pension Plans, Defined Benefit | US Government Debt Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	25,709	24,322
United States Pension Plans, Defined Benefit | Global equity Securities
Defined Benefit Plan Disclosure
Total	32,120	30,360
United States Pension Plans, Defined Benefit | Global equity Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	32,120	30,360
United States Pension Plans, Defined Benefit | Group Annuity Insurance Contracts
Defined Benefit Plan Disclosure
Total	3,166	3,071
United States Pension Plans, Defined Benefit | Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total	3,166	3,071
United States Pension Plans, Defined Benefit | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total	3,217	3,023
United States Pension Plans, Defined Benefit | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total	3,217	3,023
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Total	1,307	27,571	$ 28,141
Foreign Pension Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total		62
Foreign Pension Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	1,307	1,124
Foreign Pension Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total		26,385
Foreign Pension Plans, Defined Benefit | Group Annuity Insurance Contracts
Defined Benefit Plan Disclosure
Total		26,385
Foreign Pension Plans, Defined Benefit | Group Annuity Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure
Total		26,385
Foreign Pension Plans, Defined Benefit | Other
Defined Benefit Plan Disclosure
Total	1,307	1,124
Foreign Pension Plans, Defined Benefit | Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure
Total	$ 1,307	1,124
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents
Defined Benefit Plan Disclosure
Total		62
Foreign Pension Plans, Defined Benefit | Cash and Cash Equivalents | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure
Total		$ 62

Schedule of Defined Benefit Pla

Schedule of Defined Benefit Plans Disclosures (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure
Ending Balance	$ 325,800
Significant Unobservable Inputs (Level 3) | Group Annuity Insurance Contracts
Defined Benefit Plan Disclosure
Beginning Balance	29,456	$ 29,392
Settlements	(28,560)
Purchases of group annuity insurance contracts		709
Interest and market value adjustments	959	5,308
Benefits paid	(244)	(611)
Other	(61)	(634)
Non-U.S. currency movement	1,616	(4,708)
Ending Balance	$ 3,166	$ 29,456

Schedule of Expected Future Ben

Schedule of Expected Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2017USD ($)
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
2,018	$ 19,387
2,019	19,022
2,020	19,688
2,021	20,246
2,022	20,994
2023-2027	110,214
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
2,018	886
2,019	887
2,020	1,253
2,021	1,002
2,022	952
2023-2027	6,294
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
2,018	591
2,019	597
2,020	535
2,021	502
2,022	439
2023-2027	$ 1,665

Schedule of One Percent Point C

Schedule of One Percent Point Change in assumed Health Care Cost Trends Rate (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure
Effect of one percentage point increase on total service and interest cost components	$ 3
Effect of one percentage point increase on postretirement benefit obligations	64
Effect of one percentage point decrease on total service and interest cost components	(3)
Effect of one percentage point decrease on postretirement benefit obligations	$ (60)

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended							12 Months Ended
	Jan. 31, 2018	Jul. 31, 2017	Jan. 31, 2017	Jul. 31, 2016	Jan. 31, 2016	Jul. 31, 2015	Jan. 31, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of common stock price paid								85.00%
Stock options term								7 years
Restricted stock unit awards granted								939,000	1,471,000	1,681,000
Weighted average grant date fair value of restricted stock units granted								$ 28.91	$ 18.95	$ 17.66
Tax benefit from compensation expense								$ 10,462,000	$ 8,752,000	$ 8,528,000
Total unrecognized expense related to non-vested restricted stock unit awards and stock options								$ 42,000,000
Unrecognized expense related to non-vested restricted stock unit awards and stock options expected to be recognized over weighted average period, in years								2 years 3 months 19 days
Maximum percent of shares allowed to purchase								10.00%
Fair market value								$ 25,000
Maximum number of shares allowed to purchase								6,000
Common stock issued to employees		300,000	400,000	500,000	500,000	500,000
Value of common stock issued to employees per share		$ 25.53	$ 21.59	$ 16.74	$ 17.57	$ 16.40
Number of shares available for grant								8,605,000	9,546,000	10,914,000	12,443,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of common stock price paid								100.00%
Period of stock granted to employees and executive officers vest in equal annual installments								4 years
Cash received from employees, employee stock options exercises								$ 6,800,000	$ 2,900,000	$ 2,800,000
Tax benefit from compensation expense								$ 2,500,000	$ 800,000	$ 2,100,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted								939,000	1,471,000	1,681,000
Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments								4 years
Restricted Stock Units | Director
Share-based Compensation Arrangement by Share-based Payment Award
Period of stock granted to employees and executive officers vest in equal annual installments								1 year
Percentage of awards vesting on the first anniversary of grant date								100.00%
TSR Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period					3 years
Share-based compensation arrangement by share-based payment award, description								Capped at four times the grant date value
Minimum age of retirement to be eligible for PRSUs							60 years
Minimum years of service for retirement to be eligible for PRSUs							10 years
Restricted stock unit awards granted								100,000	100,000	200,000
Weighted average grant date fair value of restricted stock units granted								$ 35.66	$ 20.29	$ 18.21
Estimated annual dividend amount per share								0.28	0.24	0.24
Stock price								$ 28.56	$ 19.43	$ 18.10
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved					200.00%
TSR Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved					0.00%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares available for grant								3,100,000
PBIT Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Total shareholder return performance measurement period					3 years
Restricted stock unit awards granted								100,000	100,000
Weighted average grant date fair value of restricted stock units granted								$ 27.72	$ 18.71
PBIT Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved					200.00%
PBIT Performance-Based Restricted Stock Units | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of vesting of target shares upon performance achieved					0.00%
Service-Based Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted								800,000	1,200,000	1,500,000
Weighted average grant date fair value of restricted stock units granted								$ 28.19	$ 18.88	$ 17.51
Service-Based Restricted Stock Units | Non Employee Directors And Certain Employees
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted								100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted								$ 34.48	$ 18.71	$ 20.21
Service-Based Restricted Stock Units | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award
Restricted stock unit awards granted								100,000	100,000	100,000
Weighted average grant date fair value of restricted stock units granted								$ 7.13	$ 5.30	$ 4.43
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award
Common stock issued to employees	300,000
Value of common stock issued to employees per share	$ 35.59

Schedule of Estimated Fair Valu

Schedule of Estimated Fair Value of TSR Performance-Based Restricted Stock Unit Awards Assumptions (Detail) - TSR Performance-Based Restricted Stock Units	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Risk-free interest rate	1.50%	1.00%	0.80%
Expected historical volatility	26.60%	27.00%	28.20%
Dividend yield	1.00%	1.20%	1.30%
New York Stock Exchange Composite Index
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility	13.40%	13.10%
Philadelphia Semiconductor Index
Share-based Compensation Arrangement by Share-based Payment Award
Expected historical volatility			19.70%

Schedule of Estimated Fair V114

Schedule of Estimated Fair Value of Stock Options Grant Using Black Scholes Option Pricing Model (Detail) - Stock Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Expected life (years)	5 years	5 years	4 years
Risk-free interest rate	2.00%	1.40%	1.10%
Volatility-historical	27.80%	32.90%	33.40%
Dividend yield	1.00%	1.20%	1.30%

Schedule of Stock Compensation

Schedule of Stock Compensation Plan Activity (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Awarded	939	1,471	1,681
Forfeited	(109)	(233)	(284)
Outstanding at January 1	926	1,121	1,507
Granted	111	130	132
Exercised	(501)	(324)	(518)
Forfeited	0	0	0
Expired	(5)	(2)
Outstanding at December 31	531	926	1,121
Vested and expected to vest at December 31	531	926	1,121
Exercisable at December 31	233	598	779
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	3,778	4,070	4,352
Awarded	939	1,471	1,681
Vested	(1,434)	(1,530)	(1,679)
Forfeited	(109)	(233)	(284)
Non-vested at December 31	3,174	3,778	4,070

Schedule of Share Based Compens

Schedule of Share Based Compensation Total Shares Available (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Available for grant at January 1	9,546	10,914	12,443
Options granted	(111)	(130)	(132)
Restricted stock units awarded	(939)	(1,471)	(1,681)
Restricted stock units forfeited	109	233	284
Additional shares reserved	0	0	0
Available for grant at December 31	8,605	9,546	10,914

Schedule of Weighted-Average Re

Schedule of Weighted-Average Restricted Stock Unit Award Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Non-vested at January 1	$ 18.27	$ 17.66	$ 17.35
Awarded	28.91	18.95	17.66
Vested	17.90	17.36	16.93
Forfeited	20.35	17.80	17.28
Non-vested at December 31	$ 21.71	$ 18.27	$ 17.66

Schedule of Restricted Stock Un

Schedule of Restricted Stock Unit Awards Aggregate Intrinsic Value (Detail) - Restricted Stock Units - USD ($) $ / shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Vested	$ 40,649	$ 30,008	$ 32,200
Outstanding	$ 132,875	$ 95,952	$ 84,129
Expected to vest	$ 130,594	$ 91,871	$ 79,611

Schedule of Restricted Stock119

Schedule of Restricted Stock Units Weighted Average Remaining Contractual Terms (Detail) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	1 year	1 year 15 days	1 year 1 month 2 days
Expected to vest	11 months 26 days	1 year 11 days	1 year 29 days

Schedule of Weighted Average St

Schedule of Weighted Average Stock Options Exercise Price (Detail)	12 Months Ended
	Dec. 31, 2017$ / shares
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding at January 1	$ 11.93
Options granted	28.56
Options exercised	13.60
Options forfeited	3.04
Options cancelled	0
Outstanding at December 31	13.92
Exercisable at December 31	$ 2.95

Schedule of Stock Option Aggreg

Schedule of Stock Option Aggregated Intrinsic Value Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Exercised	$ 8,035	$ 3,729	$ 7,255
Outstanding	14,831	12,468	11,729
Vested and expected to vest	14,831	12,468	11,729
Exercisable	$ 9,076	$ 10,217	$ 10,716

Schedule of Stock Options Weigh

Schedule of Stock Options Weighted Average Remaining Contractual Terms (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	4 years 1 month 6 days	3 years 10 months 25 days	4 years 2 months 12 days
Vested and expected to vest	4 years 1 month 6 days	3 years 10 months 25 days	4 years 2 months 12 days
Exercisable	2 years 9 months 18 days	3 years 2 months 12 days	3 years 10 months 25 days

Schedule of Significant Option

Schedule of Significant Option Groups Outstanding (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Shares | shares	531
Options Exercisable, Shares | shares	233
Options Outstanding, Weighted-Average Exercise Price	$ 13.92
Options Exercisable, Weighted-Average Exercise Price	$ 2.95
$1.48 - $2.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	2 years 2 months 8 days
Options Outstanding, Shares | shares	99
Options Exercisable, Shares | shares	99
Range Of Exercise Prices, Lower Limit	$ 1.48
Range Of Exercise Prices, Upper Limit	2.58
Options Outstanding, Weighted-Average Exercise Price	1.81
Options Exercisable, Weighted-Average Exercise Price	$ 1.81
$2.67 - $7.71
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	3 years 2 months 1 day
Options Outstanding, Shares | shares	126
Options Exercisable, Shares | shares	126
Range Of Exercise Prices, Lower Limit	$ 2.67
Range Of Exercise Prices, Upper Limit	7.71
Options Outstanding, Weighted-Average Exercise Price	2.89
Options Exercisable, Weighted-Average Exercise Price	$ 2.89
$18.10 - $19.43
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	4 years 5 months 23 days
Options Outstanding, Shares | shares	194
Options Exercisable, Shares | shares	8
Range Of Exercise Prices, Lower Limit	$ 18.10
Range Of Exercise Prices, Upper Limit	19.43
Options Outstanding, Weighted-Average Exercise Price	18.91
Options Exercisable, Weighted-Average Exercise Price	$ 18.51
$ 28.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Weighted-Average Remaining Contractual Life (Years)	6 years 29 days
Options Outstanding, Shares | shares	112
Range Of Exercise Prices, Upper Limit	$ 28.56
Options Outstanding, Weighted-Average Exercise Price	$ 28.56

Stock Based Compensation (Detai

Stock Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 34,097	$ 30,750	$ 30,451
Income tax benefit	(10,462)	(8,752)	(8,528)
Total stock-based compensation expense after income taxes	23,635	21,998	21,923
Cost Of Revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	3,212	3,153	3,065
Engineering And Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	9,370	9,458	9,362
Selling and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 21,515	$ 18,139	$ 18,024

Savings Plan - Additional Infor

Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Savings Plan [Line Items]
Savings plan maximum percentage of employees contribution allowable	20.00%
Percentage of employer contributions vested per year	25.00%
Maximum employment period considered for vesting of employers' contribution, in years	4 years
U.S. Qualified Pension Plan
Savings Plan [Line Items]
Maximum percentage of matching contributions made by the employer	100.00%	100.00%	100.00%
Percentage of employer match on employee contribution	4.00%	4.00%	4.00%
Savings Plan
Savings Plan [Line Items]
Amounts charged to statements of operations	$ 15.3	$ 14.5	$ 13.5

Schedule of Income (Loss) Befor

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

3 Months Ended

12 Months Ended

Dec. 31, 2017

[1],[2]

Oct. 01, 2017

[3]

Jul. 02, 2017

[2],[4]

Apr. 02, 2017

[5]

Dec. 31, 2016

[6],[7]

Oct. 02, 2016

[7],[8]

Jul. 03, 2016

[7],[9]

Apr. 03, 2016

[7],[10]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Income Tax Disclosure [Line Items]

U.S.

$ 76,699

$ (341,018)

$ 56,270

Non-U.S.

447,713

285,958

196,854

Income (loss) before income taxes

$ 98,084

$ 127,437

$ 206,877

$ 92,016

$ 58,884

$ 59,681

$ (230,817)

$ 57,192

$ 524,412

$ (55,060)

$ 253,124

[1]

Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.

[2]

Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[3]

Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.

[4]

Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.

[5]

Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.

[6]

Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[7]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[8]

Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[9]

Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.

[10]

Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Schedule of Provision (Benefit)

Schedule of Provision (Benefit) for Income Taxes from Operations (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1],[2]	Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016	[6],[7]	Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Current, U.S. Federal																	$ 162,679	$ 7,750	$ 16,635
Current, Non-U.S.																	64,313	41,579	35,707
Current, State																	2,623	1,968	1,429
Current, Total																	229,615	51,297	53,771
Deferred, U.S. Federal																	43,687	(51,482)	(574)
Deferred, Non-U.S.																	(6,476)	(9,240)	(7,761)
Deferred, State																	(106)	(2,214)	1,211
Deferred, Total																	37,105	(62,936)	(7,124)
Total provision (benefit) for income taxes	$ 204,007		$ 24,017		$ 31,901		$ 6,795		$ (7,461)		$ (4,113)		$ (7,271)		$ 7,206		$ 266,720	$ (11,639)	$ 46,647
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016		Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Total (benefit) provision for income taxes	$ 204,007,000	[1],[2]	$ 24,017,000		$ 31,901,000		$ 6,795,000		$ (7,461,000)	[6],[7]	$ (4,113,000)		$ (7,271,000)		$ 7,206,000			$ 266,720,000	$ (11,639,000)	$ 46,647,000
Effective tax rate																		50.90%	21.10%	18.40%
Corporate tax rate																		35.00%	35.00%	35.00%
Provisional amount of additional income tax expense	186,000,000
Transition tax on mandatory deemed repatriation of foreign earnings																		$ 161,000,000
Expense related to remeasurement of deferred tax assets and liabilities																		33,600,000
Benefit associated with impact of correlative adjustments on tax positions																		10,300,000
Tax savings due to the tax holiday																		$ 24,800,000	$ 17,000,000	$ 11,500,000
Tax savings due to the tax holiday, per share																		$ 0.12	$ 0.08	$ 0.05
Tax holiday expiration date																		December 31, 2020
Valuation allowance amount decrease/increase																		$ 15,600,000
Valuation allowance resulted from effect of reduction in U.S. Federal corporate tax rate																		11,300,000
Valuation allowance includes net deferred tax assets	63,919,000								48,369,000									63,919,000	$ 48,369,000
Tax credit carryforwards, approximately	123,500,000																	123,500,000
Tax credits carryforwards	76,083,000								57,313,000									76,083,000	57,313,000
Unrecognized tax benefits	36,263,000								38,958,000									36,263,000	38,958,000	$ 36,792,000	$ 30,418,000
Unrecognized tax benefits, if recognized would impact effective tax rate	24,800,000																	24,800,000
Unrecognized tax benefits, if recognized would impact deferred taxes	11,500,000																	11,500,000
Accrued interest and penalties	300,000								$ 400,000									300,000	400,000
Interest and penalties related to income tax																		100,000	$ 100,000	$ 200,000
Scenario, Forecast
Income Taxes [Line Items]
Corporate tax rate																	21.00%
Do Not Expire
Income Taxes [Line Items]
Alternative minimum tax credits carryforwards	6,600,000																	6,600,000
United States
Income Taxes [Line Items]
Tax credits carryforwards, business	28,300,000																	$ 28,300,000
United States | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																		2,018
United States | Latest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																		2,037
State and Local Jurisdiction
Income Taxes [Line Items]
Tax credits carryforwards	88,600,000																	$ 88,600,000
State and Local Jurisdiction | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																		2,018
State and Local Jurisdiction | Latest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																		2,037
State and Local Jurisdiction | Do Not Expire
Income Taxes [Line Items]
Tax credits carryforwards	$ 51,400,000																	$ 51,400,000
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

Schedule of Reconciliation of E

Schedule of Reconciliation of Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
U.S. statutory federal tax rate	35.00%	35.00%	35.00%
U.S. transition tax	28.70%
Impact of rate change on deferred tax	6.40%
Uncertain tax positions	1.70%	(2.60%)	2.20%
Foreign taxes	(16.30%)	78.00%	(13.80%)
Foreign tax credits	(2.20%)	49.10%	(2.70%)
U.S. research and development credit	(1.60%)	15.80%	(3.00%)
Equity compensation	(0.80%)	(2.70%)	0.60%
Domestic production activities deduction	(0.30%)	2.30%	(1.00%)
State income taxes, net of federal tax benefit		2.30%	0.40%
Goodwill impairment		(162.10%)
U.S. alternative minimum tax credit		3.70%
Inventory cost capitalization		1.80%
Other, net	0.30%	0.50%	0.70%
Effective tax rate, Total	50.90%	21.10%	18.40%

Schedule of Components of Defer

Schedule of Components of Deferred Tax Assets Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Tax credits	$ 76,083	$ 57,313
Accruals	27,508	27,247
Pension liabilities	22,602	31,581
Inventory valuations	17,793	31,227
Deferred revenue	9,016	12,806
Equity compensation	6,861	9,922
Net operating loss carryforwards	5,440	5,244
Vacation accrual	4,747	7,874
Other	713	630
Gross deferred tax assets	170,763	183,844
Less: valuation allowance	(63,919)	(48,369)
Total deferred tax assets	106,844	135,475
Intangible assets	(16,120)	(22,887)
Depreciation	(12,293)	(17,117)
Marketable securities	(1,125)	(210)
Total deferred tax liabilities	(29,538)	(40,214)
Net deferred assets	$ 77,306	$ 95,261

Summary of Operating Loss Carry

Summary of Operating Loss Carryforwards (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	$ 0
State Operating Loss Carryforwards	71,303
Foreign Operating Loss Carryforwards	7,142
2,018
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	9,943
2,019
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	174
2,020
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	130
2,021
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	2,919
2,022
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	6,362
2023-2027
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	12,296
2028-2032
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	34,963
Beyond 2,032
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
State Operating Loss Carryforwards	4,516
Foreign Operating Loss Carryforwards	130
Non-Expiring
Operating Loss Carryforwards [Line Items]
U.S. Federal Operating Loss Carryforwards	0
Foreign Operating Loss Carryforwards	$ 7,012

Schedule of Unrecognized Tax Be

Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Beginning balance, as of January 1	$ 38,958	$ 36,792	$ 30,418
Tax positions for current year, Additions	8,208	9,766	6,626
Tax positions for prior years, Additions	199	187	792
Tax positions for prior years, Reductions	(10,573)	(1,960)	(708)
Expiration of statutes, Reductions	(325)	(3,532)
Settlements with tax authorities, Reductions	(204)	(2,295)	(336)
Ending balance as of December 31	$ 36,263	$ 38,958	$ 36,792

Operating Segment, Geographi133

Operating Segment, Geographic and Significant Customer Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017CustomerSegment	Dec. 31, 2016Customer	Dec. 31, 2015Customer
Segment Reporting Information [Line Items]
Operating segments | Segment	4
Number of customer accounted for more than ten percent of consolidated revenue | Customer	1	1	1
Semiconductor Test | Consolidated Revenue | Customer Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage	22.00%	26.00%	23.00%
Semiconductor Test | Customer 1 | Consolidated Revenue | Revenue from Rights Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage	13.00%	12.00%
Semiconductor Test | Customer 2 | Consolidated Revenue | Revenue from Rights Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk, percentage		12.00%	13.00%

Schedule of Segment Information

Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2017		Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016		Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues		$ 479,415	[1],[2]	$ 503,378		$ 696,901		$ 456,913		$ 379,989	[6],[7]	$ 410,475		$ 531,792		$ 430,994		$ 2,136,606	[11]	$ 1,753,250	[11]	$ 1,639,578	[11]
Income (loss) before taxes	[12],[13]																	524,412		(55,060)		253,124
Total assets	[14]	3,109,545								2,762,493								3,109,545		2,762,493		2,548,674
Property additions																		105,375		85,272		89,878
Depreciation and amortization expense																		108,075		120,009		140,773
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues																		1,662,549		1,368,169		1,201,530
Income (loss) before taxes	[12],[13]																	491,361		311,939		260,154
Total assets	[14]	597,480								557,546								597,480		557,546		610,869
Property additions																		87,920		70,543		79,052
Depreciation and amortization expense																		58,901		58,087		64,415
System Test
Segment Reporting Information [Line Items]
Revenues																		192,135		189,846		211,584
Income (loss) before taxes	[12],[13]																	10,306		28,916		25,101
Total assets	[14]	97,018								110,361								97,018		110,361		102,547
Property additions																		5,976		3,788		6,228
Depreciation and amortization expense																		6,646		6,551		4,391
Industrial Automation
Segment Reporting Information [Line Items]
Revenues																		170,056		99,031		41,892
Income (loss) before taxes	[12],[13]																	8,763		(16,783)		(7,574)
Total assets	[14]	368,037								317,635								368,037		317,635		344,260
Property additions																		7,044		6,755		1,465
Depreciation and amortization expense																		25,711		26,869		14,500
Wireless Test
Segment Reporting Information [Line Items]
Revenues																		111,866		96,204		184,572
Income (loss) before taxes	[12],[13]																	17,350		(371,409)		(13,830)
Total assets	[14]	59,912								62,366								59,912		62,366		427,880
Property additions																		4,435		4,186		3,133
Depreciation and amortization expense																		5,392		25,921		53,440
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) before taxes	[12],[13]																	(3,368)		(7,723)		(10,727)
Total assets	[14]	$ 1,987,098								$ 1,714,585								1,987,098		1,714,585		1,063,118
Depreciation and amortization expense																		$ 11,425		$ 2,581		$ 4,027
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[11]	Revenues attributable to a country are based on location of customer site.
[12]	Included in Corporate and Eliminations are: contingent consideration adjustments, pension and postretirement plans actuarial gains (losses), severance charges, impairment of fixed assets and expenses related to the Japan earthquake, property insurance recovery, interest income, interest expense, net foreign exchange gains (losses), and gain from the sale of an equity investment.
[13]	Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges, goodwill impairment charges and an acquired intangible assets impairment charge.
[14]	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																12 Months Ended
		Dec. 31, 2017		Oct. 01, 2017		Jul. 02, 2017		Apr. 02, 2017		Dec. 31, 2016		Oct. 02, 2016		Jul. 03, 2016		Apr. 03, 2016		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Restructuring and other-employee severance		$ 8,970	[1],[2]	$ (4,407)	[3]	$ 2,288	[2],[4]	$ 2,511	[5]	$ 5,570	[6],[7]	$ 12,177	[7],[8]	$ 2,608	[7],[9]	$ 1,587	[7],[10]	$ 9,362	$ 21,942	$ 5,080
Goodwill impairment charge										0				254,946	[7],[9]			0	254,946
Intangible assets impairment charge														83,339	[7],[9]				83,339
Pension acturial (gains) losses		3,800				2,500				2,000		(700)		700		1,200
Contingent consideration adjustment																		7,820	15,896	2,489
Other (income) expense, net-gain from the sale of an equity investment																				5,406
Restructuring and other
Segment Reporting Information [Line Items]
Building impairment and other expenses														4,200
Contingent consideration adjustment														1,400
Universal Robots
Segment Reporting Information [Line Items]
Contingent consideration adjustment		$ 6,000		$ (300)		$ 1,500		$ 600		$ 5,400		$ 8,000				$ 1,200		7,800	15,300	5,300
Acquisition related costs																				1,000
Universal Robots | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment														800
ZTEC Instruments, Inc.
Segment Reporting Information [Line Items]
Contingent consideration adjustment																				(1,600)
Avionics Interface Technologies, LLC
Segment Reporting Information [Line Items]
Contingent consideration adjustment																			600	(1,300)
Avionics Interface Technologies, LLC | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment														600
Semiconductor Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge																		4,606	9,656	10,508
Semiconductor Test | Fixed Assets [Member]
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																		1,124
Semiconductor Test | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																		1,779	2,860	499
System Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge																		1,918	630	8,324
Restructuring and other-employee severance																			(49)	1,037
Industrial Automation
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																		1,414	585
Cost of revenues-inventory step-up	[11]																			1,567
Wireless Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge																		2,190	7,207	2,500
Restructuring and other-lease impairment																		973
Restructuring and other-employee severance																			2,650
Goodwill impairment charge														254,900					254,946
Intangible assets impairment charge														$ 83,300					83,339
Corporate And Eliminations | Restructuring and other
Segment Reporting Information [Line Items]
Restructuring and other-employee severance																		530
Property insurance recovery																		(5,064)	(5,051)
Acquisition related costs																				1,104
Corporate And Eliminations | Cost of revenues
Segment Reporting Information [Line Items]
Pension acturial (gains) losses																		(2,752)	(1,025)	8,271
Corporate And Eliminations | Engineering and development
Segment Reporting Information [Line Items]
Pension acturial (gains) losses																		(2,456)	(1,234)	4,658
Corporate And Eliminations | Selling and administrative
Segment Reporting Information [Line Items]
Pension acturial (gains) losses																		(1,416)	(944)	4,826
Corporate And Eliminations | Other (income) expense, net
Segment Reporting Information [Line Items]
Other (income) expense, net-gain from the sale of an equity investment																				(5,406)
Corporate And Eliminations | Universal Robots | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment																		7,820	15,346	5,339
Corporate And Eliminations | Impairment of fixed assets and expenses related to the Japan earthquake | Restructuring and other
Segment Reporting Information [Line Items]
Building impairment and other expenses																		$ 755	5,051
Corporate And Eliminations | ZTEC Instruments, Inc. | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment																				(1,600)
Corporate And Eliminations | Avionics Interface Technologies, LLC | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment																			$ 550	$ (1,250)
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[11]	Included in the cost of revenues for the year ended December 31, 2015 is the cost for purchase accounting inventory step-up.

Schedule of Revenues by Country

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

3 Months Ended

12 Months Ended

Dec. 31, 2017

[1],[2]

Oct. 01, 2017

[3]

Jul. 02, 2017

[2],[4]

Apr. 02, 2017

[5]

Dec. 31, 2016

[6],[7]

Oct. 02, 2016

[7],[8]

Jul. 03, 2016

[7],[9]

Apr. 03, 2016

[7],[10]

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

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

Revenue from unaffiliated customers

$ 479,415

$ 503,378

$ 696,901

$ 456,913

$ 379,989

$ 410,475

$ 531,792

$ 430,994

$ 2,136,606

[11]

$ 1,753,250

[11]

$ 1,639,578

[11]

TAIWAN

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

Revenue from unaffiliated customers

[11]

687,031

653,076

436,389

CHINA

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

Revenue from unaffiliated customers

[11]

260,451

174,876

264,898

UNITED STATES

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

Revenue from unaffiliated customers

[11]

252,516

221,948

217,386

KOREA

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

Revenue from unaffiliated customers

[11]

206,819

147,882

120,224

JAPAN

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

Revenue from unaffiliated customers

[11]

169,093

135,978

128,228

Europe

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

Revenue from unaffiliated customers

[11]

163,715

117,671

111,903

MALAYSIA

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

Revenue from unaffiliated customers

[11]

124,048

103,472

76,707

PHILIPPINES

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

Revenue from unaffiliated customers

[11]

105,850

54,705

96,103

SINGAPORE

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

Revenue from unaffiliated customers

[11]

101,085

73,172

105,216

THAILAND

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

Revenue from unaffiliated customers

[11]

29,566

43,097

59,104

Rest Of The World

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

Revenue from unaffiliated customers

[11]

$ 36,432

$ 27,373

$ 23,420

[1]

Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.

[2]

Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[3]

Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.

[4]

Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.

[5]

Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.

[6]

Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[7]

Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.

[8]

Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[9]

Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.

[10]

Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.

[11]

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

Schedule of Long-Lived Assets b

Schedule of Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		$ 268,447	$ 253,821
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		198,855	189,195
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	[1]	$ 69,592	$ 64,626
[1]	As of December 31, 2017 and 2016, long-lived assets attributable to Singapore were $23.6 million and $31.5 million, respectively.

Schedule of Long-Lived Asset138

Schedule of Long-Lived Assets by Geographic Area (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 268,447	$ 253,821
SINGAPORE
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 23,600	$ 31,500

Stock Repurchase Program - Addi

Stock Repurchase Program - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2015
Stock Repurchase Programs [Line Items]
Stock repurchase program, authorized amount		$ 500,000,000
Stock Repurchased During Period, Shares		6.8	15.6
Stock Repurchased During Period, Value	$ 200,304,000	$ 146,331,000	$ 299,949,000
Treasury stock average price per share		$ 21.39	$ 19.20
Cumulative repurchases, shares	5.8	22.5
Cumulative repurchases, value	$ 200,000,000	$ 446,000,000
Common stock average price	$ 34.30	$ 19.87
Maximum
Stock Repurchase Programs [Line Items]
Stock repurchase program, authorized amount				$ 500,000,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Stock repurchase program, authorized amount			$ 500,000,000
Repurchase of stock, value		$ 200,304,000	$ 146,331,000	$ 299,949,000
Subsequent Event
Subsequent Event [Line Items]
Cash Dividends payable, amount per share	$ 0.09
Cash Dividends payable, date to be paid	Mar. 23, 2018
Cash Dividends payable, record date	Feb. 23, 2018
Stock repurchase program, authorized amount	$ 1,500,000,000
Repurchase of stock, value	$ 750,000,000

Consolidated Quarterly Statemen

Consolidated Quarterly Statements of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1],[2]	Oct. 01, 2017	[3]	Jul. 02, 2017	[2],[4]	Apr. 02, 2017	[5]	Dec. 31, 2016		Oct. 02, 2016	[7],[8]	Jul. 03, 2016	[7],[9]	Apr. 03, 2016	[7],[10]	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information [Line Items]
Products	$ 388,282		$ 412,854		$ 610,356		$ 373,204		$ 303,667	[6],[7]	$ 334,610		$ 456,832		$ 358,139		$ 1,784,695		$ 1,453,248		$ 1,340,566
Services	91,133		90,524		86,545		83,709		76,322	[6],[7]	75,865		74,960		72,855		351,911		300,002		299,012
Total revenues	479,415		503,378		696,901		456,913		379,989	[6],[7]	410,475		531,792		430,994		2,136,606	[11]	1,753,250	[11]	1,639,578	[11]
Cost of products	166,667		169,744		267,171		154,966		127,481	[6],[7]	148,266		215,795		167,555		758,548		659,097		591,772
Cost of services	39,813		38,848		38,511		37,014		33,502	[6],[7]	34,850		33,127		33,107		154,186		134,586		132,163
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	206,480		208,592		305,682		191,980		160,983	[6],[7]	183,116		248,922		200,662		912,734		793,683		723,935
Gross profit	272,935		294,786		391,219		264,933		219,006	[6],[7]	227,359		282,870		230,332		1,223,872		959,567		915,643
Selling and administrative	88,006		86,244		89,131		84,906		76,289	[6],[7]	78,794		81,425		79,174		348,287		315,682		306,313
Engineering and development	70,564		77,190		81,728		76,182		70,052	[6],[7]	71,400		76,109		73,464		305,665		291,025		292,250
Acquired intangible assets amortization	7,384		7,028		8,166		7,952		7,923	[6],[7]	8,487		16,244		19,994		30,530		52,648		69,031
Acquired intangible assets impairment													83,339						83,339
Goodwill impairment									0				254,946				0		254,946
Restructuring and other	8,970		(4,407)		2,288		2,511		5,570	[6],[7]	12,177		2,608		1,587		9,362		21,942		5,080
Total operating expenses	174,924		166,055		181,313		171,551		159,834	[6],[7]	170,858		514,671		174,219		693,844		1,019,582		672,674
Income (loss) from operations	98,011		128,731		209,906		93,382		59,172	[6],[7]	56,501		(231,801)		56,113		530,028		(60,015)		242,969
Interest income	(6,476)		(4,517)		(3,292)		(3,520)		(3,095)	[6],[7]	(2,892)		(1,666)		(1,642)		(17,805)		(9,296)		(7,214)
Interest expense	5,380		5,372		5,509		5,402		1,604	[6],[7]	633		691		710		21,663		3,637		1,876
Other (income) expense, net	1,023		439		812		(516)		1,779	[6],[7]	(921)		(9)		(147)		1,758		704		(4,817)
Income (loss) before income taxes	98,084		127,437		206,877		92,016		58,884	[6],[7]	59,681		(230,817)		57,192		524,412		(55,060)		253,124
Income tax provision (benefit)	204,007		24,017		31,901		6,795		(7,461)	[6],[7]	(4,113)		(7,271)		7,206		266,720		(11,639)		46,647
Net income (loss)	$ (105,923)		$ 103,420		$ 174,976		$ 85,221		$ 66,345	[6],[7]	$ 63,794		$ (223,546)		$ 49,986		$ 257,692		$ (43,421)		$ 206,477
Net income (loss) per common share-basic	$ (0.54)		$ 0.52		$ 0.88		$ 0.43		$ 0.33	[6],[7]	$ 0.32		$ (1.10)		$ 0.24		$ 1.30		$ (0.21)		$ 0.98
Net income (loss) per common share-diluted	(0.54)		0.52		0.87		0.42		0.33	[6],[7]	0.31		(1.10)		0.24		1.28		(0.21)		0.97
Cash dividend declared per common share	$ 0.07		$ 0.07		$ 0.07		$ 0.07		$ 0.06	[6],[7]	$ 0.06		$ 0.06		$ 0.06		$ 0.28		$ 0.24		$ 0.24
[1]	Restructuring and other includes a $6.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, $1.8 million of employee severance charges, and $1.1 million of charges for impairment of fixed assets.
[2]	Teradyne recorded pension and post retirement net actuarial gains of $2.5 million and $3.8 million for the second and fourth quarter in 2017, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[3]	Restructuring and other includes $5.1 million of property insurance recovery related to the Japan earthquake, a $0.4 million credit related to previously impaired lease termination of a Wireless Test facility in Sunnyvale, CA, and a $0.3 million credit for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $0.8 million of Japan earthquake related expenses and $0.6 million of employee severance charges.
[4]	Restructuring and other includes a $1.5 million charge for a fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.8 million of employee severance charges.
[5]	Restructuring and other includes a $1.3 million charge for a lease impairment of a Wireless Test facility in Sunnyvale, CA, a $0.6 million fair value adjustment to increase the Universal Robots acquisition contingent consideration, and $0.6 million of employee severance charges.
[6]	Restructuring and other includes a $5.4 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[7]	Teradyne recorded pension and post retirement net actuarial (gains) losses of $(1.2) million, $(0.7) million, $0.7 million and $(2.0) million for the first, second, third, and fourth quarter in 2016, respectively. See Note B: "Accounting Policies" for a discussion of Teradyne's accounting policy.
[8]	Restructuring and other includes an $8.0 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[9]	Restructuring and other includes $4.2 million for an impairment of fixed assets, $0.9 million for expenses related to an earthquake in Kumamoto, Japan, and a $1.4 million fair value adjustment to increase contingent consideration liability, of which $0.8 million was related to Universal Robots and $0.6 million was related to AIT, partially offset by $5.1 million of property insurance recovery related to the Japan earthquake.
[10]	Restructuring and other includes a $1.2 million fair value adjustment to increase the Universal Robots acquisition contingent consideration.
[11]	Revenues attributable to a country are based on location of customer site.

Consolidated Quarterly State142

Consolidated Quarterly Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment									$ 7,820	$ 15,896	$ 2,489
Severance benefit and charges	$ 1,800	$ 600	$ 800	$ 600					1,400
Impairment of fixed assets	1,100
Pension and post retirement net actuarial (gains) losses	(3,800)		(2,500)		$ (2,000)	$ 700	$ (700)	$ (1,200)
Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							1,400
Impairment of fixed assets and other expenses							4,200
Universal Robots
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment	$ 6,000	(300)	$ 1,500	600	$ 5,400	$ 8,000		$ 1,200	7,800	15,300	5,300
Universal Robots | Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							800
Avionics Interface Technologies, LLC
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment										600	$ (1,300)
Avionics Interface Technologies, LLC | Restructuring and other
Quarterly Financial Information [Line Items]
Contingent consideration fair value adjustment							600
Wireless Test
Quarterly Financial Information [Line Items]
Lease impairment				$ 1,300
Wireless Test
Quarterly Financial Information [Line Items]
Lease impairment									1,000
Previously impaired lease termination		400
Impairment of fixed assets and expenses related to the Japan earthquake
Quarterly Financial Information [Line Items]
Property insurance recovery		5,100							5,100	5,100
Impairment of fixed assets and expenses related to the Japan earthquake | Restructuring and other
Quarterly Financial Information [Line Items]
Property insurance recovery							5,100
Impairment of fixed assets and expenses related to the Japan earthquake | Earthquake Related Expenses
Quarterly Financial Information [Line Items]
Impairment of fixed assets and other expenses		$ 800							$ 800	$ 900
Impairment of fixed assets and expenses related to the Japan earthquake | Earthquake Related Expenses | Restructuring and other
Quarterly Financial Information [Line Items]
Impairment of fixed assets and other expenses							$ 900

Valuation and Qualifying Acc143

Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 2,356	$ 2,407	$ 2,491
Additions Charged to Cost and Expenses	4
Deductions	141	51	84
Balance at End of Period	2,219	2,356	2,407
Inventory Reserve
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	116,016	119,376	111,252
Additions Charged to Cost and Expenses	8,844	17,493	21,332
Other	(126)	4,417	1,680
Deductions	21,838	25,270	14,888
Balance at End of Period	102,896	116,016	119,376
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	48,369	43,039	41,737
Additions Charged to Cost and Expenses	15,571	5,413	1,322
Deductions	21	83	20
Balance at End of Period	$ 63,919	$ 48,369	$ 43,039