Accumulated Other Comprehensive Income Balances (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Other Comprehensive Income (Loss) [Line Items]
Retirement plans prior service benefit, tax	$ (125)	$ (125)
Unrealized gains on marketable securities, tax	$ 835	$ 835

The tax effect from the total of net (gain) loss, prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

No definition available.

Name:	ter_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansTax
Namespace Prefix:	ter_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant