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Medicaid lawsuit charge

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Commitments and Contingencies (Narrative) (Details) $ / shares in Units, $ in Millions				3 Months Ended			12 Months Ended
	Oct. 12, 2020 USD ($)	Oct. 11, 2020 USD ($)	Feb. 25, 2020 USD ($) $ / shares	Mar. 26, 2021 USD ($) lawsuit	Dec. 25, 2020 USD ($)	Mar. 27, 2020 USD ($)	Dec. 25, 2020 USD ($)
Loss Contingencies [Line Items]
Medicaid lawsuit (Note 11)							$ 641.1
Settlement Warrants, Fair Value Disclosure				$ 0.0	$ 0.0		0.0
Liabilities Subject to Compromise				5,914.2	4,192.6		4,192.6
Sales [Member]
Loss Contingencies [Line Items]
Medicaid lawsuit (Note 11)							536.0
Operating Expenses
Loss Contingencies [Line Items]
Medicaid lawsuit (Note 11)						$ 105.1	105.1
Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Liabilities Subject to Compromise				638.9	638.9		638.9
Boston Civil Investigative Demand [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual				0.0
Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party, Post Closing Settlement Amount, Total	$ 260.0
Loss Contingency Accrual				0.0
Medicaid Lawsuit [Member] \| Maximum
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		$ 640.0
Track 1 Cases [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements					24.0
Loss Contingency Accrual, Product Liability, Gross				6.0
Loss Contingency, Accrual, Noncurrent				$ 0.5
Opioid crisis [Member] \| Cities, Counties, and/or Other Government-related Persons/Entities [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs \| lawsuit				2,615
Opioid crisis [Member] \| Hospitals, Health Systems, Unions, Health and Welfare Fund or Third-Party Payers [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs \| lawsuit				270
Opioid crisis [Member] \| Individuals [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs \| lawsuit				124
Opioid crisis [Member] \| Schools and School Boards [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs \| lawsuit				6
Opioid crisis [Member] \| State Attorney Generals [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs \| lawsuit				17
Opioid Claimant Trust [Member]
Loss Contingencies [Line Items]
Warrant, Exercise Price \| $ / shares			$ 3.15
Restructuring Support Agreement Proposed Settlement, Year Three through Eight		150.0
Opioid Claimant Trust [Member] \| Restructuring Support Agreement [Member]
Loss Contingencies [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
Restructuring Support Agreement Proposed Settlement, Year Three through Eight		150.0
Opioid Claimant Trust [Member] \| Maximum
Loss Contingencies [Line Items]
Loss Contingency Accrual			$ 1,600.0	$ 1,600.0	$ 1,600.0		$ 1,600.0
Opioid Claimant Trust [Member] \| Maximum \| Restructuring Support Agreement [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual		1,600.0
Equity Value of Opioid Claimants' Ownership		$ 1,551.0
Senior Notes \| 5.75% Senior Notes
Loss Contingencies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.75%
Senior Notes \| 10.00% Second Lien Senior Notes
Loss Contingencies [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		10.00%
Other Ownership Interest [Member] \| Opioid Claimant Trust [Member] \| Maximum
Loss Contingencies [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			19.99%
Other Ownership Interest [Member] \| Opioid Claimant Trust [Member] \| Maximum \| Restructuring Support Agreement [Member]
Loss Contingencies [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		19.99%