Condensed Consolidated Statement of Changes in Shareholders' Equity Statement - USD ($) $ in Millions	Total	Ordinary Shares	Treasury Shares	Additional Paid-In Capital	Retained Earnings (Deficit)	Accumulated Other Comprehensive Loss
Shares, Outstanding		93,500,000	9,400,000
Beginning balance at Dec. 27, 2019	$ 1,940.7	$ 18.7	$ (1,615.7)	$ 5,562.5	$ (2,016.9)	$ (7.9)
Net loss	(50.2)				(50.2)
Other Comprehensive Income (Loss), Net of Tax	(1.3)					(1.3)
Vesting of restricted shares (in shares)		100,000	0
Vesting of restricted shares (in usd)	(0.1)	$ 0.0	$ 0.0	(0.1)
Share-based compensation	6.7			6.7
Ending balance at Mar. 27, 2020	1,895.8	18.7	(1,615.7)	5,569.1	(2,067.1)	(9.2)
Beginning balance at Dec. 27, 2019	1,940.7	18.7	(1,615.7)	5,562.5	(2,016.9)	(7.9)
Net loss					(791.7)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(0.5)
Ending balance at Sep. 25, 2020	1,165.7	$ 18.8	$ (1,616.1)	5,580.0	(2,808.6)	(8.4)
Shares, Outstanding		93,600,000	9,400,000
Beginning balance at Mar. 27, 2020	1,895.8	$ 18.7	$ (1,615.7)	5,569.1	(2,067.1)	(9.2)
Net loss	(933.1)				(933.1)
Other Comprehensive Income (Loss), Net of Tax	0.4					0.4
Vesting of restricted shares (in shares)		500,000	100,000
Vesting of restricted shares (in usd)	(0.2)	$ 0.1	$ (0.3)	0.0
Share-based compensation	6.6			6.6
Ending balance at Jun. 26, 2020	969.5	$ 18.8	$ (1,616.0)	5,575.7	(3,000.2)	(8.8)
Shares, Outstanding		94,100,000	9,500,000
Net loss	191.6				191.6
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0.4
Other Comprehensive Income (Loss), Net of Tax	0.4					0.4
Vesting of restricted shares (in shares)		0	0
Vesting of restricted shares (in usd)	(0.1)	$ 0.0	$ (0.1)	0.0
Share-based compensation	4.3			4.3
Ending balance at Sep. 25, 2020	$ 1,165.7	$ 18.8	$ (1,616.1)	5,580.0	(2,808.6)	(8.4)
Shares, Outstanding		94,100,000	9,500,000
Shares, Outstanding		94,100,000	9,500,000
Beginning balance, ordinary shares (in shares) at Dec. 25, 2020	94,111,303
Beginning balance, treasury shares (in shares) at Dec. 25, 2020	9,506,147
Beginning balance at Dec. 25, 2020	$ 1,019.2	$ 18.8	$ (1,616.1)	5,587.6	(2,961.5)	(9.6)
Net loss	(143.9)				(143.9)
Other Comprehensive Income (Loss), Net of Tax	0.1					0.1
Vesting of restricted shares (in shares)		0	0
Vesting of restricted shares (in usd)	(0.1)	$ 0.0	$ 0.0	(0.1)
Share-based compensation	3.6			3.6
Ending balance at Mar. 26, 2021	$ 878.9	18.8	(1,616.1)	5,591.1	(3,105.4)	(9.5)
Beginning balance, ordinary shares (in shares) at Dec. 25, 2020	94,111,303
Beginning balance, treasury shares (in shares) at Dec. 25, 2020	9,506,147
Beginning balance at Dec. 25, 2020	$ 1,019.2	18.8	(1,616.1)	5,587.6	(2,961.5)	(9.6)
Net loss	(513.4)				(513.4)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (0.9)
Ending balance, ordinary shares (in shares) at Sep. 24, 2021	94,290,199
Ending balance, treasury shares (in shares) at Sep. 24, 2021	9,567,767
Ending balance at Sep. 24, 2021	$ 513.4	$ 18.9	$ (1,616.1)	5,596.0	(3,474.9)	(10.5)
Shares, Outstanding		94,100,000	9,500,000
Beginning balance at Mar. 26, 2021	878.9	$ 18.8	$ (1,616.1)	5,591.1	(3,105.4)	(9.5)
Net loss	(105.8)				(105.8)
Other Comprehensive Income (Loss), Net of Tax	0.3					0.3
Vesting of restricted shares (in shares)		200,000	100,000
Vesting of restricted shares (in usd)	0.2	$ 0.1	$ 0.0	0.1
Share-based compensation	2.4			2.4
Ending balance at Jun. 25, 2021	776.0	$ 18.9	$ (1,616.1)	5,593.6	(3,211.2)	(9.2)
Shares, Outstanding		94,300,000	9,600,000
Net loss	(263.7)				(263.7)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent						(1.3)
Other Comprehensive Income (Loss), Net of Tax	(1.3)					(1.3)
Share-based compensation	$ 2.4			2.4
Ending balance, ordinary shares (in shares) at Sep. 24, 2021	94,290,199
Ending balance, treasury shares (in shares) at Sep. 24, 2021	9,567,767
Ending balance at Sep. 24, 2021	$ 513.4	$ 18.9	$ (1,616.1)	$ 5,596.0	$ (3,474.9)	$ (10.5)
Shares, Outstanding		94,300,000	9,600,000