Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 27, 2019	Dec. 28, 2018	Dec. 29, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (7.7)	$ 37.0	$ 75.1
Other comprehensive income (loss):
Change in cumulative translation adjustment	(0.4)	(1.3)	1.2
Change in pension net actuarial loss	(0.3)
Cash flow hedges:
Change in fair value of derivatives		(0.1)	1.2
Adjustment for net loss realized and included in net income		(1.0)	(0.2)
Total change in unrealized gain (loss) on derivative instruments		(1.1)	1.0
Total other comprehensive income (loss), net of tax	(0.7)	(2.4)	2.2
Other comprehensive income (loss), net of tax, attributable to noncontrolling interests	1.7	0.4
Comprehensive income (loss) attributable to UCT	$ (10.1)	$ 34.2	$ 77.3