Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Apr. 01, 2012
Commitments And Contingencies [Abstract]
Aggregate purchase commitments	$ 273.2
Purchase commitments less than one year	$ 272.8
Purchase commitments period	less than one year

The floor amount as of the balance sheet date that the entity must expend to satisfy the terms of disclosed arrangements (excluding long-term commitments) in which the entity has agreed to expend funds to procure goods or services from one or more suppliers, other than under a long-term purchase commitment or an unconditional purchase obligation.

No definition available.

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