Net Income Per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
Apr. 03, 2016	Apr. 05, 2015
Net Income Loss Per Common Share
Exercise of stock options	0.3	0.2

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