Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Mar. 29, 2020
Goodwill [Line Items]
Foreign currency translation adjustment	$ (6,349)
Goodwill	1,178,997	$ 1,172,499
Accumulated impairment losses	(762,566)	(762,566)
Goodwill	416,431	409,933
Autoguide LLC
Goodwill [Line Items]
Goodwill	(149)
Industrial Automation
Goodwill [Line Items]
Foreign currency translation adjustment	(6,354)
Goodwill	396,483	389,980
Goodwill	396,483	389,980
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	5
Goodwill	261,996	262,001
Accumulated impairment losses	(260,540)	(260,540)
Goodwill	1,456	1,461
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Goodwill	$ 10,516	$ 10,516