Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 25, 2021	Jun. 26, 2020	Jun. 25, 2021	Jun. 26, 2020	Dec. 25, 2020
Income Taxes [Line Items]
Income tax (benefit) expense	$ (33.5)	$ 161.3	$ (49.9)	$ 142.4
Increase (decrease) tax benefit	194.8		(192.3)
(Loss) income from continuing operations before income taxes	$ (139.7)	$ (789.3)	$ (300.3)	$ (864.9)
Effective tax rate	24.00%	(20.40%)	16.60%	(16.50%)
Current Income Tax Expense (Benefit)	$ 23.6	$ 146.5	$ (36.6)	$ (168.8)
Deferred Income Tax Expense (Benefit)	9.9	$ 307.8	(13.3)	$ (311.2)
Income Taxes Paid, Net					$ 39.9
Unrecognized tax benefits	348.7		348.7		349.0
Unrecognized tax benefits, net increase			(0.3)
Unrecognized tax benefits, which if favorably settled would benefit the effective tax rate	73.3		73.3
Interest accrued on unrecognized tax benefits	19.1		19.1		$ 16.7
Unrecognized tax benefits that would impact effective tax rate, upper bound of change	34.1		34.1
Income tax penalties and interest accrued that would impact effective tax rate, upper bound of change	15.1		15.1
Increase (Decrease) Tax Expense (Benefit), Change in Operating Income	28.2		43.6
Increase (Decrease), Tax Expense (Benefit), CARES Act	37.7		(48.7)
Increase (Decrease), Tax Expense (Benefit), Uncertain Tax Positions	2.9		5.1
Increase (Decrease), Income Tax Expense (Benefit), Separation Costs, Reorganization Items, and Restructuring Charges	5.0		6.1
Increase (Decrease) Tax Benefit, Intercompany Financing Reorganization	6.3		(6.3)
Increase (Decrease), Tax Expense (Benefit), Valuation Allowances	$ 202.7		202.7
Proceeds from Income Tax Refunds			59.6
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities			0.2
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions			7.2
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations			7.3
CARES Act [Member]
Income Taxes [Line Items]
Proceeds from Income Tax Refunds			$ 77.6