Net Income Per Common Share - Additional Information (Detail) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 29, 2013	Sep. 30, 2012	Sep. 29, 2013	Sep. 30, 2012
Net Income Loss Per Common Share
Exercise of stock options	0.4	0.3	0.4	0.3
Restricted stock units exercise to purchase shares		0.1		0.4

Issuance of ordinary shares upon exercise of employee stock options and restricted stock units, shares.

No definition available.

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