Segment Information (Schedule Of Segment Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 01, 2012		Apr. 03, 2011
Segment Reporting Information [Line Items]
Net revenues	$ 396,668		$ 377,161
Income (loss) from continuing operations before income taxes	41,244	[1],[2]	75,424	[1],[2]
Semiconductor Test [Member]
Segment Reporting Information [Line Items]
Net revenues	267,588		319,250
Income (loss) from continuing operations before income taxes	34,998	[1],[2]	76,926	[1],[2]
Systems Test Group [Member]
Segment Reporting Information [Line Items]
Net revenues	97,752		57,911
Income (loss) from continuing operations before income taxes	21,978	[1],[2]	5,491	[1],[2]
Wireless Test [Member]
Segment Reporting Information [Line Items]
Net revenues	31,328
Income (loss) from continuing operations before income taxes	(12,312)	[1],[2]
Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before income taxes	$ (3,420)	[1],[2]	$ (6,993)	[1],[2]

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

[2] Included in the income (loss) from continuing operations before income taxes for each of the segments are charges for the three months ended April 1, 2012 and April 3, 2011 that include restructuring and other, net, and provision for excess and obsolete inventory, as follows: