Net Loss Per Share - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 29, 2024	Mar. 31, 2023
Numerator:
Net loss attributable to UCT	$ (9.4)	$ (3.4)
Shares used in computation — basic:
Weighted average common shares outstanding (in shares)	44.6	44.8
Shares used in computation — diluted:
Weighted average common shares outstanding (in shares)	44.6	44.8
Effect of potential dilutive securities:
Employee stock plans	0.0	0.0
Shares used in computing diluted net loss per share (in shares)	44.6	44.8
Net loss per share attributable to UCT — basic (in dollars per share)	$ (0.21)	$ (0.08)
Net loss per share attributable to UCT — diluted (in dollars per share)	$ (0.21)	$ (0.08)