Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jul. 02, 2017		Jul. 03, 2016		Jul. 02, 2017		Jul. 03, 2016		Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues		$ 696,901		$ 531,792		$ 1,153,814		$ 962,787
Income (loss) before income taxes	[1],[2]	206,877		(230,817)		298,893		(173,625)
Total assets		3,030,225	[3]	2,407,858	[3]	3,030,225	[3]	2,407,858	[3]	$ 2,762,493
Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		593,152		435,323		948,679		775,588
Income (loss) before income taxes	[1],[2]	211,278		121,163		309,244		194,417
Total assets	[3]	766,395		731,394		766,395		731,394
Industrial Automation
Segment Reporting Information [Line Items]
Revenues		39,337		25,102		75,610		41,848
Income (loss) before income taxes	[1],[2]	(1,081)		(4,501)		(3,652)		(11,669)
Total assets	[3]	349,023		346,290		349,023		346,290
System Test
Segment Reporting Information [Line Items]
Revenues		36,732		48,940		76,578		102,610
Income (loss) before income taxes	[1],[2]	(5,692)		8,992		(8,451)		18,484
Total assets	[3]	108,083		91,374		108,083		91,374
Wireless Test
Segment Reporting Information [Line Items]
Revenues		27,680		22,427		52,947		42,741
Income (loss) before income taxes	[1],[2]	4,514		(356,505)		6,046		(376,645)
Total assets	[3]	62,900		61,618		62,900		61,618
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) before income taxes	[1],[2]	(2,142)		34		(4,294)		1,788
Total assets	[3]	$ 1,743,824		$ 1,177,182		$ 1,743,824		$ 1,177,182

[1] Included in income (loss) before taxes are charges and credits related to restructuring and other, inventory charges, goodwill impairment charges and acquired intangible assets impairment charge.

[2] Interest income, interest expense, contingent consideration adjustments, pension and postretirement plan actuarial gains and other income (expense) are included in Corporate and Eliminations.

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