Schedule of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 29, 2026		Mar. 30, 2025		Dec. 31, 2025
Segment Reporting Information [Line Items]
Revenues		$ 1,282,494		$ 685,680
Cost of revenues		493,604		265,074
Engineering and development		119,897		107,605
Selling and marketing		98,132		87,948
General and administrative		42,083		41,386
Other segment items	[1],[2]	63,102		64,643
Income (loss) before taxes	[2]	465,676		119,024
Total assets		4,433,827	[3]	3,705,837	[3]	$ 4,183,599
Property additions		64,733		65,186
Depreciation and amortization expense		32,655		30,302
Product Test
Segment Reporting Information [Line Items]
Revenues		80,435		74,189
Operating Segments
Segment Reporting Information [Line Items]
Revenues		1,282,494		685,680
Cost of revenues		493,604		265,074
Engineering and development		119,897		107,605
Selling and marketing		98,132		87,948
General and administrative		42,083		41,386
Other segment items	[1],[2]	56,983		56,406
Income (loss) before taxes	[2]	471,795		127,261
Total assets	[3]	3,136,005		2,345,121
Property additions		64,733		65,186
Depreciation and amortization expense		32,581		30,312
Operating Segments | Semiconductor Test
Segment Reporting Information [Line Items]
Revenues		1,110,801		542,504
Cost of revenues		413,855		202,747
Engineering and development		93,296		80,211
Selling and marketing		63,831		51,697
General and administrative		26,839		26,552
Other segment items	[1],[2]	44,928		25,495
Income (loss) before taxes	[2]	468,052		155,802
Total assets	[3]	2,087,713		1,396,660
Property additions		58,493		59,732
Depreciation and amortization expense		24,689		22,865
Operating Segments | Robotics
Segment Reporting Information [Line Items]
Revenues		91,258		68,987
Cost of revenues		45,185		32,292
Engineering and development		12,262		15,855
Selling and marketing		21,188		24,514
General and administrative		8,758		9,865
Other segment items	[1],[2]	4,829		23,638
Income (loss) before taxes	[2]	(964)		(37,177)
Total assets	[3]	692,054		742,621
Property additions		2,831		2,676
Depreciation and amortization expense		4,327		5,941
Operating Segments | Product Test
Segment Reporting Information [Line Items]
Revenues		80,435		74,189
Cost of revenues		34,564		30,035
Engineering and development		14,339		11,539
Selling and marketing		13,113		11,737
General and administrative		6,486		4,969
Other segment items	[1],[2]	7,226		7,273
Income (loss) before taxes	[2]	4,707		8,636
Total assets	[3]	356,238		205,840
Property additions		3,409		2,778
Depreciation and amortization expense		3,565		1,506
Corporate And Eliminations
Segment Reporting Information [Line Items]
Revenues		0		0
Cost of revenues		0		0
Engineering and development		0		0
Selling and marketing		0		0
General and administrative		0		0
Other segment items	[1],[2]	6,119		8,237
Income (loss) before taxes	[2]	(6,119)		(8,237)
Total assets	[3]	1,297,822		1,360,716
Property additions		0		0
Depreciation and amortization expense		$ 74		$ (10)

[1] For each reportable segment, the other segment items category includes equity and variable compensation, acquired intangible assets amortization, inventory step-up, and restructuring and other charges.

[2] Included in Corporate and Eliminations are interest income, interest expense, net foreign exchange gains (losses), intercompany eliminations, severance charges, pension and postretirement plan actuarial gains (losses), acquisition and divestiture related expenses, and ERP implementation related costs.

[3] Total assets are attributable to each segment. Corporate assets consist of cash and cash equivalents, marketable securities, and certain other assets.