Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
Apr. 01, 2018	Feb. 26, 2018	Dec. 31, 2017
Goodwill [Line Items]
Foreign currency translation adjustment	$ 8,035
Goodwill	1,038,266		$ 1,014,577
Accumulated impairment losses	(762,566)		(762,566)
Goodwill	275,700		252,011
Energid Technologies Corporation
Goodwill [Line Items]
Energid acquisition	15,654
Goodwill		$ 15,700
Wireless Test
Goodwill [Line Items]
Goodwill	361,819		361,819
Accumulated impairment losses	(353,843)		(353,843)
Goodwill	7,976		7,976
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	8,035
Goodwill	257,208		233,519
Goodwill	257,208		233,519
Industrial Automation \| Energid Technologies Corporation
Goodwill [Line Items]
Energid acquisition	15,654
System Test
Goodwill [Line Items]
Goodwill	158,699		158,699
Accumulated impairment losses	(148,183)		(148,183)
Goodwill	10,516		10,516
Semiconductor Test
Goodwill [Line Items]
Goodwill	260,540		260,540
Accumulated impairment losses	$ (260,540)		$ (260,540)

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

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