Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ 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
Common stock, shares, beginning balance (in shares) at Dec. 30, 2022			45.2
Treasury stock, shares, beginning balance (in shares) at Dec. 30, 2022					0.9
Beginning balance at Dec. 30, 2022	$ 937.0	$ 887.9	$ 0.1	$ 530.8	$ (15.4)	$ 377.8	$ (5.4)	$ 49.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			0.6
Issuance under employee stock plans	0.8	0.8		0.8
Shares transfer to employee stock plans (in shares)					(0.5)
Repurchase of shares (in shares)			(1.1)		1.1
Repurchase of shares	(29.6)	(29.6)			$ (29.6)
Stock-based compensation expense	12.1	12.1		12.1
Employees’ taxes paid upon vesting of restricted stock units (in shares)			(0.1)
Employees’ taxes paid upon vesting of restricted stock units	(2.2)	(2.2)		(2.2)
Dividend payments to a joint venture shareholder	(0.2)							(0.2)
Net income (loss)	(22.2)	(31.1)				(31.1)		8.9
Other comprehensive income (loss)	1.5	1.0					1.0	0.5
Ending balance at Dec. 29, 2023	897.2	838.9	$ 0.1	541.5	$ (45.0)	346.7	(4.4)	58.3
Common stock, shares, ending balance (in shares) at Dec. 29, 2023			44.6
Treasury stock, shares, ending balance (in shares) at Dec. 29, 2023					1.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			0.6
Issuance under employee stock plans	2.0	2.0		2.0
Repurchase of shares (in shares)			0.0
Stock-based compensation expense	17.4	17.4		17.4
Employees’ taxes paid upon vesting of restricted stock units (in shares)			(0.1)
Employees’ taxes paid upon vesting of restricted stock units	(2.5)	(2.5)		(2.5)
Dividend payments to a joint venture shareholder	(0.5)							(0.5)
Net income (loss)	34.5	23.7				23.7		10.8
Other comprehensive income (loss)	(12.3)	(5.9)					(5.9)	(6.4)
Ending balance at Dec. 27, 2024	$ 935.8	873.6	$ 0.1	558.4	$ (45.0)	370.4	(10.3)	62.2
Common stock, shares, ending balance (in shares) at Dec. 27, 2024	45.1		45.1
Treasury stock, shares, ending balance (in shares) at Dec. 27, 2024	1.5				1.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance under employee stock plans (in shares)			0.6
Issuance under employee stock plans	$ 2.2	2.2		2.2
Repurchase of shares (in shares)			(0.2)		0.2
Repurchase of shares	(3.4)	(3.4)			$ (3.4)
Stock-based compensation expense	19.2	19.2		19.2
Employees’ taxes paid upon vesting of restricted stock units	(1.1)	(1.1)		(1.1)
Dividend payments to a joint venture shareholder	(0.1)							(0.1)
Net income (loss)	(171.6)	(181.2)				(181.2)		9.6
Other comprehensive income (loss)	3.1	1.7					1.7	1.4
Ending balance at Dec. 26, 2025	$ 784.1	$ 711.0	$ 0.1	$ 578.7	$ (48.4)	$ 189.2	$ (8.6)	$ 73.1
Common stock, shares, ending balance (in shares) at Dec. 26, 2025	45.5		45.5
Treasury stock, shares, ending balance (in shares) at Dec. 26, 2025	1.7				1.7