Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Total Stockholders’ Equity of UCT	Common Stock	Additional Paid-in Capital	Treasury shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance at Dec. 30, 2022	$ 937.0	$ 887.9	$ 0.1	$ 530.8	$ (15.4)	$ 377.8	$ (5.4)	$ 49.1
Common stock, shares, beginning balance (in shares) at Dec. 30, 2022			45,200,000
Treasury stock, shares, beginning balance (in shares) at Dec. 30, 2022					900,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			500,000
Employees' taxes paid upon vesting of restricted stock units (in shares)			(100,000)
Employees' taxes paid upon vesting of restricted stock units	(2.2)	(2.2)		(2.2)
Repurchase of shares (in shares)			(800,000)		(800,000)
Repurchase shares	(23.7)	(23.7)	$ (23.7)		$ (23.7)
Stock-based compensation expense	4.7	4.7		4.7
Net income (loss)	(7.8)	(12.8)				(12.8)		5.0
Dividend payments to a joint venture shareholder	(0.1)							(0.1)
Other comprehensive income (loss)	(1.7)	(4.1)					(4.1)	2.4
Ending balance at Jun. 30, 2023	906.2	849.8	$ 0.1	533.3	$ (39.1)	365.0	(9.5)	56.4
Treasury stock, shares, ending balance (in shares) at Jun. 30, 2023					1,700,000
Common stock, shares, ending balance (in shares) at Jun. 30, 2023			44,800,000
Beginning balance at Mar. 31, 2023	925.0	870.7	$ 0.1	534.3	$ (29.6)	374.4	(8.5)	54.3
Common stock, shares, beginning balance (in shares) at Mar. 31, 2023			44,800,000
Treasury stock, shares, beginning balance (in shares) at Mar. 31, 2023					1,400,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			400,000
Issuance under employee stock plans	0.0
Employees' taxes paid upon vesting of restricted stock units (in shares)			(100,000)
Employees' taxes paid upon vesting of restricted stock units	(2.0)	(2.0)		(2.0)
Repurchase of shares (in shares)			(300,000)		(300,000)
Repurchase shares	(9.5)	(9.5)	$ (9.5)		$ (9.5)
Stock-based compensation expense	1.0	1.0		1.0
Net income (loss)	(8.2)	(9.4)				(9.4)		1.2
Dividend payments to a joint venture shareholder	(0.1)							(0.1)
Other comprehensive income (loss)	0.0	(1.0)					(1.0)	1.0
Ending balance at Jun. 30, 2023	906.2	849.8	$ 0.1	533.3	$ (39.1)	365.0	(9.5)	56.4
Treasury stock, shares, ending balance (in shares) at Jun. 30, 2023					1,700,000
Common stock, shares, ending balance (in shares) at Jun. 30, 2023			44,800,000
Beginning balance at Dec. 29, 2023	$ 897.2	838.9	$ 0.1	541.5	$ (45.0)	346.7	(4.4)	58.3
Common stock, shares, beginning balance (in shares) at Dec. 29, 2023	44,600,000		44,600,000
Treasury stock, shares, beginning balance (in shares) at Dec. 29, 2023	1,500,000				1,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			500,000
Issuance under employee stock plans	$ 0.9	0.9		0.9
Employees' taxes paid upon vesting of restricted stock units (in shares)			100,000
Employees' taxes paid upon vesting of restricted stock units	(2.2)	(2.2)		(2.2)
Repurchase of shares (in shares)			0
Stock-based compensation expense	8.0	8.0		8.0
Net income (loss)	14.2	9.7				9.7		4.5
Dividend payments to a joint venture shareholder	(0.1)							(0.1)
Other comprehensive income (loss)	(6.3)	(3.0)					(3.0)	(3.3)
Ending balance at Jun. 28, 2024	$ 911.7	852.3	$ 0.1	548.2	$ (45.0)	356.4	(7.4)	59.4
Treasury stock, shares, ending balance (in shares) at Jun. 28, 2024	1,500,000				1,500,000
Common stock, shares, ending balance (in shares) at Jun. 28, 2024	45,000,000.0		45,000,000.0
Beginning balance at Mar. 29, 2024	$ 889.1	830.9	$ 0.1	545.0	$ (45.0)	337.3	(6.5)	58.2
Common stock, shares, beginning balance (in shares) at Mar. 29, 2024			44,600,000
Treasury stock, shares, beginning balance (in shares) at Mar. 29, 2024					1,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			500,000
Issuance under employee stock plans	0.9	0.9		0.9
Employees' taxes paid upon vesting of restricted stock units (in shares)			100,000
Employees' taxes paid upon vesting of restricted stock units	(2.2)	(2.2)		(2.2)
Repurchase of shares (in shares)			0
Stock-based compensation expense	4.5	4.5		4.5
Net income (loss)	21.5	19.1				19.1		2.4
Dividend payments to a joint venture shareholder	(0.1)							(0.1)
Other comprehensive income (loss)	(2.0)	(0.9)					(0.9)	(1.1)
Ending balance at Jun. 28, 2024	$ 911.7	$ 852.3	$ 0.1	$ 548.2	$ (45.0)	$ 356.4	$ (7.4)	$ 59.4
Treasury stock, shares, ending balance (in shares) at Jun. 28, 2024	1,500,000				1,500,000
Common stock, shares, ending balance (in shares) at Jun. 28, 2024	45,000,000.0		45,000,000.0