Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jul. 03, 2016		Jul. 05, 2015		Jul. 03, 2016		Jul. 05, 2015		Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues		$ 531,792		$ 512,739		$ 962,787		$ 855,140
Income (loss) before income taxes	[1],[2]	(230,817)		132,136		(173,625)		174,574
Total assets		2,407,858	[3]	2,692,807	[3]	2,407,858	[3]	2,692,807	[3]	$ 2,548,674
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		435,323		400,315		775,588		671,232
Income (loss) before income taxes	[1],[2]	121,163		129,546		194,417		172,671
Total assets	[3]	731,394		649,087		731,394		649,087
Wireless Test
Segment Reporting Information [Line Items]
Revenues		22,427		62,879		42,741		96,927
Income (loss) before income taxes	[1],[2]	(356,505)		6,841		(376,645)		(3,600)
Total assets	[3]	61,618		485,857		61,618		485,857
System Test
Segment Reporting Information [Line Items]
Revenues		48,940		45,822		102,610		83,258
Income (loss) before income taxes	[1],[2]	8,992		(4,333)		18,484		(3,328)
Total assets	[3]	91,374		95,544		91,374		95,544
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) before income taxes	[1],[2]	34		1,782		1,788		10,531
Total assets	[3]	1,177,182		1,104,043		1,177,182		1,104,043
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		25,102		3,723		41,848		3,723
Income (loss) before income taxes	[1],[2]	(4,501)		(1,700)		(11,669)		(1,700)
Total assets	[3]	$ 346,290		$ 358,276		$ 346,290		$ 358,276

[1] Included in the income (loss) before income taxes for each of the segments are charges related to inventory and other.

[2] Interest income, interest expense, and other (income) expense, net are included in Corporate and Eliminations.

[3] Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.