Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 29, 2026 Segment
Segment Reporting Information [Line Items]
Reportable segments	3
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The CODM uses business segment income (loss) before income taxes predominantly in the annual budgeting and forecasting process. The CODM also uses this measure when making decisions about the allocation of operating and capital resources to each segment. The accounting policies of the business segments are the same as those described in Teradyne’s Annual Report on Form 10-K in Note B: “Accounting Policies.”