Segment Information (Schedule Of Segment Information) (Details) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jul. 03, 2011		Jul. 04, 2010		Jul. 03, 2011		Jul. 04, 2010
Net revenues	$ 410,519		$ 445,271		$ 787,680		$ 764,609
Income (loss) from continuing operations before income taxes	97,729	[1],[2]	132,073	[1],[2]	171,339	[1],[2]	186,002	[1],[2]
Semiconductor Test [Member]
Net revenues	343,096		413,059		662,346		702,736
Income (loss) from continuing operations before income taxes	92,477	[1],[2]	141,911	[1],[2]	167,893	[1],[2]	206,997	[1],[2]
Systems Test Group [Member]
Net revenues	67,423		32,212		125,334		61,873
Income (loss) from continuing operations before income taxes	9,125	[1],[2]	(5,845)	[1],[2]	14,313	[1],[2]	(11,472)	[1],[2]
Corporate And Eliminations [Member]
Income (loss) from continuing operations before income taxes	$ (3,873)	[1],[2]	$ (3,993)	[1],[2]	$ (10,867)	[1],[2]	$ (9,523)	[1],[2]

[1] Included in the income (loss) from continuing operations before income taxes for each of the segments are charges for the three months and six months ended July 3, 2011 and July 4, 2010 that include restructuring and other, net, and provision for excess and obsolete inventory, as follows:

[2] Interest income and interest expense and other are included in Corporate and Eliminations.