Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jul. 01, 2022	Jun. 30, 2023	Jul. 01, 2022
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (8.2)	$ (21.7)	$ (7.8)	$ 9.1
Other comprehensive income (loss):
Change in cumulative translation adjustment, net of tax	0.4	(8.9)	(1.7)	(12.0)
Change in pension net actuarial gain, net of tax	(0.4)	0.0	(0.2)	0.0
Change in fair value of derivatives, net of tax	0.0	(1.4)	0.2	(1.1)
Total other comprehensive loss	0.0	(10.3)	(1.7)	(13.1)
Comprehensive loss	(8.2)	(32.0)	(9.5)	(4.0)
Comprehensive income, attributable to noncontrolling interests	2.2	3.4	7.4	6.3
Comprehensive loss attributable to UCT	$ (10.4)	$ (35.4)	$ (16.9)	$ (10.3)