Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2023	Apr. 01, 2022
Numerator:
Net income (loss) attributable to UCT	$ (3.4)	$ 27.9
Shares used in computation — basic:
Weighted average common shares outstanding	44.8	44.9
Shares used in computation — diluted:
Weighted average common shares outstanding	44.8	44.9
Dilutive effect of common shares outstanding subject to repurchase	0	0.7
Shares used in computing diluted net income per share	44.8	45.6
Net income (loss) per share attributable to UCT - basic	$ (0.08)	$ 0.62
Net income (loss) per share attributable to UCT - diluted	$ (0.08)	$ 0.61