Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Shares [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total stock holder's Equity of UCT [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 27, 2019	$ 452.5	$ 0.1	$ 300.9	$ (3.3)	$ 140.3	$ (1.3)	$ 436.7	$ 15.8
Beginning balance, Shares at Dec. 27, 2019		39.9		0.6
Stock-based compensation expense	3.1		3.1				3.1
Net income	10.5				9.4		9.4	1.1
Other comprehensive loss	(3.3)					(3.3)	(3.3)
Ending balance at Mar. 27, 2020	462.8	$ 0.1	304.0	$ (3.3)	149.7	(4.6)	445.9	16.9
Ending balance, Shares at Mar. 27, 2020		39.9		0.6
Beginning balance at Dec. 25, 2020	551.2	$ 0.1	312.8	$ (3.3)	217.9	5.1	532.6	18.6
Beginning balance, Shares at Dec. 25, 2020		40.6		0.6
Stock-based compensation expense	3.5		3.5				3.5
Net income	25.6				25.0		25.0	0.6
Dividend payments to a joint venture shareholder	(0.2)							(0.2)
Other comprehensive loss	(3.5)					(3.5)	(3.5)
Ending balance at Mar. 26, 2021	$ 576.6	$ 0.1	$ 316.3	$ (3.3)	$ 242.9	$ 1.6	$ 557.6	$ 19.0
Ending balance, Shares at Mar. 26, 2021		40.6		0.6