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

[1] Includes $3.1 million and $1.8 million in 2021 and 2020, respectively, for leases of Teradyne’s systems recognized outside Accounting Standards Codification (“ASC”) 606 “Revenue from Contracts with Customers.”