Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2024	Sep. 29, 2023	Sep. 27, 2024	Sep. 29, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 0.3	$ (12.8)	$ 14.5	$ (20.6)
Other comprehensive income (loss):
Change in cumulative translation adjustment, net of tax	6.4	(2.1)	0.1	(3.8)
Change in pension net actuarial gain, net of tax	0.0	(0.2)	0.0	(0.4)
Change in fair value of derivatives, net of tax	0.0	0.0	0.0	0.2
Total other comprehensive income (loss)	6.4	(2.3)	0.1	(4.0)
Comprehensive income (loss)	6.7	(15.1)	14.6	(24.6)
Comprehensive income, attributable to noncontrolling interests	5.5	0.6	6.7	8.0
Comprehensive income (loss) attributable to UCT	$ 1.2	$ (15.7)	$ 7.9	$ (32.6)