Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Jun. 28, 2020
Goodwill [Line Items]
Foreign currency translation adjustment	$ 5,721
Goodwill	1,178,997	$ 1,184,569
Accumulated impairment losses	(762,566)	(762,566)
Goodwill	416,431	422,003
Autoguide LLC
Goodwill [Line Items]
Goodwill acquisition	(149)
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	5,671
Goodwill	396,483	402,005
Goodwill	396,483	402,005
Industrial Automation \| Autoguide LLC
Goodwill [Line Items]
Goodwill acquisition	(149)
Wireless Test
Goodwill [Line Items]
Goodwill	361,819	361,819
Accumulated impairment losses	(353,843)	(353,843)
Goodwill	7,976	7,976
Semiconductor Test
Goodwill [Line Items]
Foreign currency translation adjustment	50
Goodwill	261,996	262,046
Accumulated impairment losses	(260,540)	(260,540)
Goodwill	1,456	1,506
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Goodwill	$ 10,516	$ 10,516

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.

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