Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 25, 2020	Dec. 27, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 126.4	$ 80.4	$ (7.7)
Other comprehensive income (loss):
Change in cumulative translation adjustment	(5.0)	6.5	(0.4)
Change in pension net actuarial gain / (loss)	0.4	(0.1)	(0.3)
Cash flow hedges:
Change in fair value of derivatives	(0.7)
Total other comprehensive income (loss), net of tax	(5.3)	6.4	(0.7)
Other comprehensive income, net of tax, attributable to noncontrolling interests	6.9	2.8	1.7
Comprehensive income (loss) attributable to UCT	$ 114.2	$ 84.0	$ (10.1)