Operating Segments and Enterprise-Wide Information - Operating Results by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 26, 2022	Mar. 27, 2021
Segment Reporting Information [Line Items]
Revenues	$ 197,174	$ 186,636
Gross profit	$ 94,224	$ 76,706
Gross margin	47.80%	41.10%
Probe Cards
Segment Reporting Information [Line Items]
Revenues	$ 159,983	$ 158,898
Systems
Segment Reporting Information [Line Items]
Revenues	37,191	27,738
Operating segments | Probe Cards
Segment Reporting Information [Line Items]
Revenues	159,983	158,898
Gross profit	$ 77,202	$ 70,315
Gross margin	48.30%	44.30%
Operating segments | Systems
Segment Reporting Information [Line Items]
Revenues	$ 37,191	$ 27,738
Gross profit	$ 19,407	$ 13,599
Gross margin	52.20%	49.00%
Operating segments | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0
Gross profit	$ (2,385)	$ (7,208)
Gross margin