Net Income Per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended	6 Months Ended
Jun. 29, 2025	Jun. 30, 2024	Jun. 29, 2025	Jun. 30, 2024
Employee Stock Option [Member]
Net Income Loss Per Common Share
Exercise of stock options	1.4	0.1	1.9	0.5

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

No definition available.

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