Net Income Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2022	Jun. 25, 2021	Jul. 01, 2022	Jun. 25, 2021
Numerator:
Net income attributable to UCT	$ (25.1)	$ 17.1	$ 2.8	$ 42.1
Shares used in computation — basic:
Weighted average common shares outstanding	45.2	43.3	45.1	41.9
Shares used in computation — diluted:
Weighted average common shares outstanding	45.2	43.3	45.1	41.9
Dilutive effect of common shares outstanding subject to repurchase		1.0	0.6	1.0
Shares used in computing diluted net income per share	45.2	44.3	45.7	42.9
Net income per share attributable to UCT — basic	$ (0.56)	$ 0.39	$ 0.06	$ 1.00
Net income per share attributable to UCT — diluted	$ (0.56)	$ 0.39	$ 0.06	$ 0.98