Net Income (Loss) Per Share - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2024	Jun. 30, 2023	Jun. 28, 2024	Jun. 30, 2023
Numerator:
Net income (loss) attributable to UCT	$ 19.1	$ (9.4)	$ 9.7	$ (12.8)
Shares used in computation — basic:
Weighted average common shares outstanding (in shares)	44.9	44.7	44.7	44.8
Shares used in computation — diluted:
Weighted average common shares outstanding (in shares)	44.9	44.7	44.7	44.8
Effect of potential dilutive securities:
Employee stock plans (in shares)	0.5	0.0	0.6	0.0
Shares used in computing diluted net loss per share (in shares)	45.4	44.7	45.3	44.8
Net income (loss) per share attributable to UCT — basic (in dollars per share)	$ 0.43	$ (0.21)	$ 0.22	$ (0.29)
Net income (loss) per share attributable to UCT — diluted (in dollars per share)	$ 0.42	$ (0.21)	$ 0.21	$ (0.29)