Schedule of Segment Reporting Information by Segment Charges (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Acquisition related costs	$ 500	$ 800	$ 2,300	$ 4,100
Restructuring and other-employee severance	(6,500)	1,710	(11,792)	3,785
Contingent consideration adjustment	7,800	800	(16,460)	(9,236)
Universal Robots (UR)
Segment Reporting Information [Line Items]
Contingent consideration adjustment		24,600
Semiconductor Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	1,867	2,071	5,319	5,851
Semiconductor Test | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance		1,716	1,009	7,657
System Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge			1,129	812
Industrial Automation
Segment Reporting Information [Line Items]
Acquisition related costs		811	1,330	811
Cost of revenues-inventory charge			508	680
Industrial Automation | Severance And Benefits
Segment Reporting Information [Line Items]
Restructuring and other-employee severance			604
Wireless Test
Segment Reporting Information [Line Items]
Cost of revenues-inventory charge	724	716	1,892	2,179
Corporate And Eliminations
Segment Reporting Information [Line Items]
Selling and administrative – equity modification charge	2,108		2,108
Corporate And Eliminations | Restructuring and other
Segment Reporting Information [Line Items]
Acquisition related costs	816		928	3,318
Corporate And Eliminations | Universal Robots (UR) | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment		$ (768)		$ (9,236)
Corporate And Eliminations | Mobile Industrial Robots (MiR) | Restructuring and other
Segment Reporting Information [Line Items]
Contingent consideration adjustment	$ (7,759)		$ (16,427)