Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Mar. 31, 2024
Goodwill [Line Items]
Goodwill	$ 1,178,218	$ 1,170,142
Accumulated impairment losses	(762,566)	(762,566)
Foreign currency translation adjustment	(8,076)
Total Goodwill	415,652	407,576
Robotics
Goodwill [Line Items]
Goodwill	395,463	387,502
Accumulated impairment losses	0	0
Foreign currency translation adjustment	(7,962)
Total Goodwill	395,463	387,502
Wireless Test
Goodwill [Line Items]
Goodwill	361,819	361,819
Accumulated impairment losses	(353,843)	(353,843)
Foreign currency translation adjustment	0
Total Goodwill	7,976	7,976
Semiconductor Test
Goodwill [Line Items]
Goodwill	262,237	262,123
Accumulated impairment losses	(260,540)	(260,540)
Foreign currency translation adjustment	(114)
Total Goodwill	1,697	1,583
System Test
Goodwill [Line Items]
Goodwill	158,699	158,699
Accumulated impairment losses	(148,183)	(148,183)
Foreign currency translation adjustment	0
Total Goodwill	$ 10,516	$ 10,516