Segment and Geographical Data (Schedule of Net Sales from External Costumers by Product) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 25, 2020		Dec. 27, 2019
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	$ 2,213.4		$ 3,162.5
Medicaid lawsuit (Note 19)			641.1
Sales [Member]
Segment Reporting Information [Line Items]
Medicaid lawsuit (Note 19)	[1]	0.0	(536.0)	[2]	0.0
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 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 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
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Medicaid lawsuit (Note 19)	[1]	0.0	(641.1)		0.0
Hydrocodone (API) and hydrocodone-containing tablets | 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)		82.7	98.0		76.3
Oxycodone (API) and oxycodone-containing tablets | 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)		68.5	68.4		74.9
Acetaminophen (API) | 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)		215.9	213.0		189.9
Other controlled substances | 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)		272.7	289.9		352.5
Acthar Gel (1) | 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)	[3]	593.6	767.9		952.7
Inomax | 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)		448.5	574.1		571.4
Ofirmev | 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)		28.9	276.5		384.0
Therakos | 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)		266.5	238.6		246.9
Amitiza | 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)	[4]	196.9	188.8		208.5
BioVectra Inc [Member] | 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)					40.1
Other Products | 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)	[5]	12.6	13.7		60.3
Other Products | 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)		$ 22.0	$ 20.5		$ 45.1

[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] Fiscal 2020 includes the prospective change to the Medicaid rebate calculation of $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.

[4] Amitiza net sales consist of both product and royalty net sales. Refer to Note 4 for further details on Amitiza's revenues.

[5] Fiscal 2019 includes $40.1 million of net sales related to BioVectra prior to the completion of the sale of this business in November 2019. Refer to Note 5 for further details.