CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				9 Months Ended
	Oct. 03, 2021		Sep. 27, 2020		Oct. 03, 2021		Sep. 27, 2020
Revenues:
Total revenues	$ 950,501	[1]	$ 819,484	[1]	$ 2,817,835	[2],[3]	$ 2,362,500	[2]
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	379,500		360,556		1,138,227		1,026,549
Gross profit	571,001		458,928		1,679,608		1,335,951
Operating expenses:
Selling and administrative	134,829		115,840		404,812		340,488
Engineering and development	107,220		94,909		317,644		274,170
Acquired intangible assets amortization	5,355		6,219		16,293		25,052
Restructuring and other	1,197		(27,701)		(3,426)		1,915
Total operating expenses	248,601		189,267		735,323		641,625
Income from operations	322,400		269,661		944,285		694,326
Non-operating (income) expense:
Interest income	(626)		(1,071)		(2,066)		(5,189)
Interest expense	3,785		6,237		15,354		17,831
Other (income) expense, net	21,486		764		25,223		3,595
Income before income taxes	297,755		263,731		905,774		678,089
Income tax provision	41,037		41,013		115,225		90,274
Net income	$ 256,718		$ 222,718		$ 790,549		$ 587,815
Net income per common share:
Basic	$ 1.56		$ 1.34		$ 4.77		$ 3.54
Diluted	$ 1.41		$ 1.21		$ 4.26		$ 3.23
Weighted average common shares—basic	164,583		166,014		165,690		166,131
Weighted average common shares—diluted	181,987		184,338		185,492		181,777
Product [Member]
Revenues:
Total revenues	$ 825,448		$ 697,745		$ 2,437,901		$ 2,043,281
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	333,229		300,174		989,859		882,902
Service [Member]
Revenues:
Total revenues	125,053		121,739		379,934		319,219
Cost of revenues:
Total cost of revenues (exclusive of acquired intangible assets amortization shown separately below)	$ 46,271		$ 60,382		$ 148,368		$ 143,647

[1] Includes $3.8 million and $1.7 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.

[2] Includes $11.1 million and $6.1 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside ASC 606 “Revenue from Contracts with Customers.

[3] The (loss) before income taxes for the nine months ended October 3, 2021 for Industrial Automation has been decreased and Corporate and Other has been increased to correctly eliminate a $10.1 million immaterial error in the three and six months ended July 4, 2021 related to intercompany charges. The error is not material to any historical periods.