Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 1,200,167	$ 1,216,425
Accumulated impairment losses	(762,566)	(762,566)
Foreign currency translation adjustment	(16,258)
Goodwill	437,601	453,859
Industrial Automation
Goodwill [Line Items]
Goodwill	417,596	433,752
Accumulated impairment losses	0	0
Foreign currency translation adjustment	(16,156)
Goodwill	417,596	433,752
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Foreign currency translation adjustment	0
Goodwill	10,516	10,516
Wireless Test
Goodwill [Line Items]
Goodwill	361,819	361,819
Accumulated impairment losses	(353,843)	(353,843)
Foreign currency translation adjustment	0
Goodwill	7,976	7,976
Semiconductor Test
Goodwill [Line Items]
Goodwill	262,053	262,155
Accumulated impairment losses	(260,540)	(260,540)
Foreign currency translation adjustment	(102)
Goodwill	$ 1,513	$ 1,615