Consolidated Statement of Changes in Shareholders' Equity Statement - USD ($) $ in Millions	Total	Ordinary Shares	Treasury Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance, shares at Dec. 30, 2016		118,200,000	13,500,000
Beginning balance, value at Dec. 30, 2016	$ 4,984.3	$ 23.6	$ (919.8)	$ 5,424.0	$ 529.0	$ (72.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	2,134.4				2,134.4
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(72.1)				(72.1)
Currency translation adjustments	11.3					11.3
Change in derivatives, net of tax	1.0					1.0
Minimum pension liability, net of tax	45.8					(45.8)
Unrecognized gain on investments	1.5					1.5
Treasury Stock, Shares, Retired		(26,500,000)
Stock Repurchased and Retired During Period, Value	$ 0.0	$ (5.3)		(5.3)
Treasury Stock, Shares, Retired			(26,500,000)
Share options exercised, shares	113,605	100,000
Share options exercised, value	$ 4.1	$ 0.0		4.1
Vesting of restricted shares, shares		400,000
Vesting of restricted shares, value	(0.1)	$ (0.1)
Treasury Stock, Shares, Acquired			18,900,000
Treasury Stock, Value, Acquired, Cost Method	(651.7)		$ 651.7
Share-based compensation	59.2			59.2
Stock Issued During Period, Value, Treasury Stock Reissued	(4.1)		$ (6.8)		2.7
Ending balance, shares at Dec. 29, 2017		92,200,000	5,900,000
Ending balance, value at Dec. 29, 2017	6,522.0	$ 18.4	$ (1,564.7)	5,492.6	2,588.6	(12.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(3,607.0)				(3,607.0)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	1.1				2.6	(1.5)
Currency translation adjustments	(12.2)					(12.2)
Change in derivatives, net of tax	0.7					0.7
Minimum pension liability, net of tax	1.6					(1.6)
Unrecognized gain on investments	$ 0.0
Share options exercised, shares	39,949
Share options exercised, value	$ 1.0			1.0
Vesting of restricted shares, shares		500,000	100,000
Vesting of restricted shares, value	2.2	$ (0.1)	$ 2.3
Treasury Stock, Shares, Acquired			3,600,000
Treasury Stock, Value, Acquired, Cost Method	(55.2)		$ 55.2
Share-based compensation	$ 34.6			34.6
Stock Issued During Period, Shares, Treasury Stock Reissued	(200,000)
Stock Issued During Period, Value, Treasury Stock Reissued	$ (2.9)		$ (4.8)		(1.9)
Ending balance, shares at Dec. 28, 2018		92,700,000	9,400,000
Ending balance, value at Dec. 28, 2018	2,887.3	$ 18.5	$ (1,617.4)	5,528.2	(1,017.7)	(24.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(996.5)				(996.5)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0.0				(0.5)	0.5
Currency translation adjustments	18.3					18.3
Change in derivatives, net of tax	1.8					1.8
Minimum pension liability, net of tax	(4.2)					4.2
Unrecognized gain on investments	$ 0.0
Share options exercised, shares	45,324
Share options exercised, value	$ 0.6			0.6
Vesting of restricted shares, shares		800,000	200,000
Vesting of restricted shares, value	2.5	$ (0.2)	$ 2.6	0.1
Share-based compensation	$ 33.8			33.8
Stock Issued During Period, Shares, Treasury Stock Reissued	(200,000)
Stock Issued During Period, Value, Treasury Stock Reissued	$ (2.1)		$ (4.3)		(2.2)
Ending balance, shares at Dec. 27, 2019		93,500,000	9,400,000
Ending balance, value at Dec. 27, 2019	$ 1,940.7	$ 18.7	$ (1,615.7)	$ 5,562.5	$ (2,016.9)	$ (7.9)