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Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Sep. 27, 2020
Goodwill [Line Items]
Foreign currency translation adjustment	$ 18,970
Goodwill	1,178,997	$ 1,197,818
Accumulated impairment losses	(762,566)	(762,566)
Goodwill	416,431	435,252
Autoguide LLC
Goodwill [Line Items]
Goodwill acquisition	(149)
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	18,881
Goodwill	396,483	415,215
Goodwill	396,483	415,215
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	89
Goodwill	261,996	262,085
Accumulated impairment losses	(260,540)	(260,540)
Goodwill	1,456	1,545
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Goodwill	$ 10,516	$ 10,516

X

- Definition

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.

+ References

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-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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