Condensed Consolidated Statements of Comprehensive Income (loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 26, 2021	Mar. 27, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 25.6	$ 10.5
Other comprehensive loss:
Change in cumulative translation adjustment	(2.8)	(3.2)
Change in fair value of derivatives	(0.7)	(0.1)
Total other comprehensive loss	(3.5)	(3.3)
Other comprehensive income, attributable to noncontrolling interests	0.6	1.1
Comprehensive income attributable to UCT	$ 21.5	$ 6.1