Segment and Geographical Data (Schedule of Segment Reporting Information by Business Segment) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 25, 2020		Dec. 27, 2019
Segment Reporting Information [Line Items]
Assets		$ 8,916.3	$ 9,715.4
Net sales (includes refined estimate of the retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)		2,208.8	2,213.4		$ 3,162.5
Operating income (loss)		(202.9)	(651.6)		(1,822.2)
Intangible asset amortization		(581.1)	(771.2)		(853.4)
Restructuring and related charges, net		(29.0)	(49.8)		1.7
Other Asset Impairment Charges		(154.9)	(63.5)		(388.0)
Opioid-related litigation settlement loss (gain) (Note 19)		125.0	(43.4)		1,643.4
Depreciation and amortization		675.8	885.2		951.1
Restructuring and related costs, accelerated depreciation		2.1	12.3		0.0
Medicaid lawsuit (Note 19)			641.1
Employee Benefits and Share-based Compensation		(10.2)	(25.3)		(33.8)
Medicaid Lawsuit [Member]
Segment Reporting Information [Line Items]
Decrease in revenue			40.4
Sales [Member]
Segment Reporting Information [Line Items]
Medicaid lawsuit (Note 19)	[1]	0.0	(536.0)	[2]	0.0
Specialty Brands [Member]
Segment Reporting Information [Line Items]
Restructuring and related charges, net		(0.1)	(0.1)		13.7
Specialty Generics [Member]
Segment Reporting Information [Line Items]
Restructuring and related charges, net		(4.9)	(0.1)		(10.0)
Operating Segments
Segment Reporting Information [Line Items]
Net sales (includes refined estimate of the retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)		2,208.8	2,749.4		3,162.5
Operating income (loss)		920.7	1,222.1		1,378.6
Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales (includes refined estimate of the retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)	[1]	1,547.0	2,059.6		2,423.8
Operating income (loss)		812.8	1,015.7		1,210.1
Depreciation and amortization		597.7	799.3		862.4
Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales (includes refined estimate of the retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)		661.8	689.8		738.7
Operating income (loss)		107.9	206.4		168.5
Depreciation and amortization		78.1	85.9		88.7
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Corporate and allocated expenses	[3]	(129.6)	(166.1)		(102.3)
Intangible asset amortization		(675.8)	(885.2)		(951.1)
Restructuring and related charges, net		(26.9)	(37.5)		1.7
Other Asset Impairment Charges		(154.9)	(63.5)		(388.0)
Separation costs	[4]	1.2	93.4		63.9
R&D upfront payment	[5]	0.0	(5.0)		(20.0)
Opioid-related litigation settlement loss (gain) (Note 19)		(125.0)	43.4		(1,643.4)
Medicaid lawsuit (Note 19)	[1]	$ 0.0	$ (641.1)		$ 0.0

[1] Specialty Brands net sales for fiscal 2020 includes the prospective change to the Medicaid rebate calculation, which served to reduce Acthar Gel net sales by $40.4 million for the period from June 15, 2020 through December 25, 2020. See Note 19 for further detail on the status of the Medicaid lawsuit.

[2] Excludes the $105.1 million that is reflected as a component of operating expenses as it represents a pre-acquisition contingency related to the portion of the liability that arose from sales of Acthar Gel prior to the Company's acquisition of Questcor in August 2014. See Note 19 for further detail on the status of the Medicaid lawsuit.

[3] Includes administration expenses and certain compensation, legal, environmental and other costs not charged to the Company's reportable segments.

[4] Represents costs included in SG&A expenses, primarily related to professional fees and costs incurred in preparation for the Chapter 11 proceedings. As of the Petition Date, professional fees directly related to the Chapter 11 proceedings that were previously reflected as separation costs are being classified on a go-forward basis as reorganization items, net.

[5] Represents R&D expense incurred related to an upfront payment made to acquire product rights in Japan for terlipressin during fiscal 2020 and an upfront payment made to Silence in connection with the license and collaboration agreement entered into in fiscal 2019. See Note 6 for further information.