Schedule of Restricted Stock Unit Awards Aggregate Intrinsic Value (Detail) (Restricted Stock Units, USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding	$ 83,949	$ 79,598	$ 97,762
Expected to vest	$ 78,718	$ 75,860	$ 90,283

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested And Expected To Vest Intrinsic Value

No definition available.

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Namespace Prefix:	ter_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant