Net Income Per Common Share - Additional Information (Detail) - Employee Stock Option [Member] - shares	3 Months Ended
Mar. 29, 2026	Mar. 30, 2025
Net Income Loss Per Common Share
Exercise of stock options		500,000
Maximum [Member]
Net Income Loss Per Common Share
Exercise of stock options	100,000

Stock issued during period shares sale of stock and exercise of stock options.

No definition available.

Name:	ter_StockIssuedDuringPeriodSharesSaleOfStockAndExerciseOfStockOptions
Namespace Prefix:	ter_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration