Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	9 Months Ended
	Oct. 04, 2015	Oct. 04, 2015	Jun. 11, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill beginning balance	$ 273,438
Foreign currency translation adjustment	(2,113)
Goodwill Ending balance	498,346
Goodwill		$ 1,005,966		$ 781,058
Accumulated impairment losses		(507,620)		(507,620)
Goodwill Ending balance	498,346	498,346		273,438
Universal Robots
Goodwill [Line Items]
Universal Robots acquisition	226,501
Universal Robots adjustment	520
Goodwill Ending balance			$ 227,021
Wireless Test
Goodwill [Line Items]
Goodwill beginning balance	262,922
Goodwill Ending balance	262,922
Goodwill		361,819		361,819
Accumulated impairment losses		(98,897)		(98,897)
Goodwill Ending balance	262,922	262,922		262,922
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	(2,113)
Goodwill Ending balance	224,908
Goodwill		224,908
Goodwill Ending balance	224,908	224,908
Industrial Automation | Universal Robots
Goodwill [Line Items]
Universal Robots acquisition	226,501
Universal Robots adjustment	520
System Test
Goodwill [Line Items]
Goodwill beginning balance	10,516
Goodwill Ending balance	10,516
Goodwill		158,699		158,699
Accumulated impairment losses		(148,183)		(148,183)
Goodwill Ending balance	$ 10,516	10,516		10,516
Semiconductor Test
Goodwill [Line Items]
Goodwill		260,540		260,540
Accumulated impairment losses		$ (260,540)		$ (260,540)