Disaggregated Revenue by Primary Geographical Market, Major Product Line and Timing of Revenue Recognition (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total	[2]	$ 2,294,965	[1]	$ 2,100,802	[1]	$ 2,136,606
Semiconductor Test
Disaggregation of Revenue [Line Items]
Total		1,552,571		1,492,417		1,662,549
System Test
Disaggregation of Revenue [Line Items]
Total		287,455	[1]	216,132	[1]	192,135
Industrial Automation
Disaggregation of Revenue [Line Items]
Total		298,139		261,452		170,056
Wireless Test
Disaggregation of Revenue [Line Items]
Total		157,315	[1]	132,006	[1]	$ 111,866
Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(515)		(1,205)
Point in Time
Disaggregation of Revenue [Line Items]
Total	[1]	1,993,077		1,815,171
Point in Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	237,686		167,418
Point in Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	148,322		122,536
Point in Time | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(515)		(1,205)
Over Time
Disaggregation of Revenue [Line Items]
Total	[1]	301,888		285,631
Over Time | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	49,769		48,714
Over Time | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	8,993		9,470
Americas
Disaggregation of Revenue [Line Items]
Total	[1]	338,384		288,379
Americas | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	129,840		96,763
Americas | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	24,234		19,166
Americas | Corporate and Other
Disaggregation of Revenue [Line Items]
Total	[1]	(515)		(1,205)
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total	[1]	228,071		235,977
Europe, Middle East and Africa | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	24,789		28,380
Europe, Middle East and Africa | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	6,532		4,968
Asia Pacific
Disaggregation of Revenue [Line Items]
Total	[1]	1,728,510		1,576,446
Asia Pacific | System Test
Disaggregation of Revenue [Line Items]
Total	[1]	132,826		90,989
Asia Pacific | Wireless Test
Disaggregation of Revenue [Line Items]
Total	[1]	126,549		107,872
SOC | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,286,440		1,218,949
SOC | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,070,375		1,010,493
SOC | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	216,065		208,456
SOC | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	73,257		78,498
SOC | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	60,302		72,572
SOC | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	1,152,881		1,067,879
Memory | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	266,131		273,468
Memory | Point in Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	247,221		259,366
Memory | Over Time | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	18,910		14,102
Memory | Americas | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	23,826		17,353
Memory | Europe, Middle East and Africa | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	3,591		10,851
Memory | Asia Pacific | Semiconductor Test
Disaggregation of Revenue [Line Items]
Total	[1]	238,714		245,264
Universal Robots (UR) | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	248,467		234,095
Universal Robots (UR) | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	244,515		231,895
Universal Robots (UR) | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	3,952		2,200
Universal Robots (UR) | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	70,165		68,938
Universal Robots (UR) | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	110,496		106,776
Universal Robots (UR) | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	67,806		58,381
MiR | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	44,403		24,115
MiR | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	44,329		24,115
MiR | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	74
MiR | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	14,438		7,326
MiR | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	20,452		10,839
MiR | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	9,513		5,950
AutoGuide | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,378
AutoGuide | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,144
AutoGuide | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	234
AutoGuide | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,378
AutoGuide | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	0
Energid | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	3,891		3,242
Energid | Point in Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]			553
Energid | Over Time | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	3,891		2,689
Energid | Americas | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,761		1,540
Energid | Europe, Middle East and Africa | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	1,909		1,591
Energid | Asia Pacific | Industrial Automation
Disaggregation of Revenue [Line Items]
Total	[1]	$ 221		$ 111

[1] Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.

[2] Revenues attributable to a country are based on location of customer site.