Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	217.6
Purchase commitments less than one year	214.4
Maximum
Purchase Commitment, Excluding Long-term Commitment
Purchase commitments period	1 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