Subsequent Events (Details) - USD ($) $ in Millions				3 Months Ended	9 Months Ended	12 Months Ended
	Oct. 12, 2020	Oct. 11, 2020	Feb. 25, 2020	Dec. 25, 2020	Sep. 25, 2020	Dec. 27, 2019
Subsequent Event [Line Items]
Long-term Debt					$ 0.0	$ 4,788.3
Opioid Claimant Trust [Member]
Subsequent Event [Line Items]
Litigation Settlement, Amount Awarded to Other Party, Settlement Closing Amount			$ 300.0
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Year One & Two			200.0
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Year Three through Eight			150.0
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Total			$ 1,300.0
Opioid Claimant Trust [Member] | Maximum
Subsequent Event [Line Items]
Loss Contingency Accrual						1,600.0
Opioid Claimant Trust [Member] | Maximum | Other Ownership Interest [Member]
Subsequent Event [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			19.99%
Medicaid Lawsuit [Member]
Subsequent Event [Line Items]
Loss Contingency Accrual					0.0
Subsequent Event [Member] | Medicaid Lawsuit [Member]
Subsequent Event [Line Items]
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Total	$ 260.0
Subsequent Event [Member] | Medicaid Lawsuit [Member] | Maximum
Subsequent Event [Line Items]
Loss Contingency, Estimate of Possible Loss		$ 640.0
Subsequent Event [Member] | Restructuring Support Agreement [Member]
Subsequent Event [Line Items]
Litigation Settlement, Amount Awarded to Other Party		150.0
Notes Reduction		1,300.0
Subsequent Event [Member] | Restructuring Support Agreement [Member] | Opioid Claimant Trust [Member]
Subsequent Event [Line Items]
Litigation Settlement, Amount Awarded to Other Party, Settlement Closing Amount		450.0
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Year One & Two		200.0
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Year Three through Eight		150.0
Subsequent Event [Member] | Restructuring Support Agreement [Member] | Opioid Claimant Trust [Member] | Maximum
Subsequent Event [Line Items]
Loss Contingency Accrual		1,600.0
Equity Value of Opioid Claimants' Ownership		$ 1,551.0
Subsequent Event [Member] | Restructuring Support Agreement [Member] | Opioid Claimant Trust [Member] | Maximum | Other Ownership Interest [Member]
Subsequent Event [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		19.99%
Unsecured Debt
Subsequent Event [Line Items]
Interest Paid, Excluding Capitalized Interest, Operating Activities					$ 64.2	$ 147.3
Unsecured Debt | Subsequent Event [Member]
Subsequent Event [Line Items]
Interest Paid, Excluding Capitalized Interest, Operating Activities				$ 28.8
Unsecured Debt | Subsequent Event [Member] | Restructuring Support Agreement [Member]
Subsequent Event [Line Items]
Holders of Principal Debt, Percentage		84.00%
Secured Debt | Subsequent Event [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)	200.00%
Secured Debt | Subsequent Event [Member] | Restructuring Support Agreement [Member]
Subsequent Event [Line Items]
Long-term Debt		$ 375.0
Long-term Debt, Term		7 years