Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Oct. 02, 2016		Oct. 04, 2015		Oct. 02, 2016		Oct. 04, 2015		Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues		$ 410,475		$ 465,994		$ 1,373,261		$ 1,321,133
Income (loss) before income taxes	[1],[2]	59,681		87,408		(113,945)		261,981
Total assets		2,365,687	[3]	2,661,884	[3]	2,365,687	[3]	2,661,884	[3]	$ 2,548,674
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		322,021		325,516		1,097,608		996,748
Income (loss) before income taxes	[1],[2]	67,710		73,957		262,127		246,627
Total assets	[3]	522,529		591,445		522,529		591,445
System Test
Segment Reporting Information [Line Items]
Revenues		37,030		69,062		139,640		152,320
Income (loss) before income taxes	[1],[2]	1,550		13,751		20,033		10,423
Total assets	[3]	90,713		109,078		90,713		109,078
Wireless Test
Segment Reporting Information [Line Items]
Revenues		27,919		55,359		70,660		152,285
Income (loss) before income taxes	[1],[2]	1,049		2,997		(375,596)		(603)
Total assets	[3]	65,953		447,461		65,953		447,461
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		23,505		16,057		65,353		19,780
Income (loss) before income taxes	[1],[2]	(4,695)		(4,847)		(16,364)		(6,547)
Total assets	[3]	340,030		360,068		340,030		360,068
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) before income taxes	[1],[2]	(5,933)		1,550		(4,145)		12,081
Total assets	[3]	$ 1,346,462		$ 1,153,832		$ 1,346,462		$ 1,153,832

[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.