Liabilities Subject to Compromise (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 25, 2021	Dec. 25, 2020
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		$ 5,900.4	$ 4,192.6
Lease rejection
Schedule of Liabilities Subject to Compromise [Line Items]
Increase (Decrease) Other current and non-current liabilities		34.8
Contingent Consideration
Schedule of Liabilities Subject to Compromise [Line Items]
Increase (Decrease) Other current and non-current liabilities		15.6
Accounts Payable
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)	[1]	47.3	61.9
Interest Payable, Current
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		35.2	35.2
Long-term Debt
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)	[2],[3]	3,441.9	1,660.7
Long-term Debt | Term Loans due Sept 2024 and Feb 2025
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		1,781.2
Medicaid Lawsuit [Member]
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		635.7	638.9
Opioid-related litigation settlement liability
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		1,600.0	1,600.0
Other current and non-current liabilities
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)	[4]	107.6	163.5
Liability, Defined Benefit Plan, Noncurrent
Schedule of Liabilities Subject to Compromise [Line Items]
Liabilities subject to compromise (Note 2)		$ 32.7	$ 32.4

[1] Pre-petition accounts payable balances have been repaid under effectuated trade agreements pursuant to the critical vendor motion approved by the Bankruptcy Court.

[2] In accordance with the Joinder and Amendment to the RSA entered into in March 2021, $1,781.2 million of outstanding senior secured term loans are classified as LSTC in the Company's unaudited condensed consolidated balance sheets as of June 25, 2021

[3] In connection with the Company’s Chapter 11 Cases, $3,441.9 million and $1,660.7 million outstanding secured and unsecured debt instruments have been reclassified to LSTC in the Company's unaudited condensed consolidated balance sheets as of June 25, 2021 and December 25, 2020, respectively. Up to the date of reclassification to LSTC, the Company continued to accrue interest expense in relation to the unsecured debt instruments reclassified to LSTC. The Company continues to accrue and pay interest on the outstanding secured debt instruments classified as LSTC in conjunction with the cash collateral order. Refer to Note 2 for further information

[4] The decrease in other current and non-current liabilities was primarily attributable to the Bankruptcy Court's approval of the Company's rejection of its Bedminster facility lease, which resulted in a $34.8 million adjustment to the carrying value of the respective lease liability in LSTC to reflect the estimated allowed claim amount. The remaining decrease was primarily attributable to a decrease of $15.6 million in the fair value of contingent consideration related to an asset for which the Company is no longer pursuing further development. Refer to Note 12 for further information on the valuation of contingent consideration.