Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 25, 2020		Dec. 27, 2019	Dec. 28, 2018
Disaggregation of Revenue [Line Items]
Revenue Reserves		$ 272.8	$ 235.4		$ 337.4	$ 405.4
Revenue Reserve Provision		2,166.0	2,154.3		2,437.7
Capitalized Contract Cost, Gross		25.8	25.8
Revenue Reserve Payments or Credits		(2,128.6)	(2,792.3)		(2,505.7)
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
Capitalized Contract Cost, Amortization		6.1	5.5
Medicaid lawsuit charge			(641.1)
Sales [Member]
Disaggregation of Revenue [Line Items]
Medicaid lawsuit charge	[1]	0.0	536.0	[2]	0.0
Operating Expense [Member]
Disaggregation of Revenue [Line Items]
Medicaid lawsuit charge		$ 0.0	$ (105.1)		$ 0.0
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred over Time		20.60%	21.10%		18.20%
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred at Point in Time		79.40%	78.90%		81.80%
Royalty [Member]
Disaggregation of Revenue [Line Items]
Net sales (includes refined estimate of the retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)		$ 102.4	$ 70.3		$ 81.3
Sales Returns and Allowances
Disaggregation of Revenue [Line Items]
Revenue Reserves		21.5	26.6		28.4	34.0
Revenue Reserve Provision		23.7	28.9		22.2
Revenue Reserve Payments or Credits		(28.8)	(30.7)		(27.8)
Medicaid lawsuit charge			0.0
Rebates and Chargebacks [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		241.8	196.5		295.8	354.3
Revenue Reserve Provision		2,087.1	2,065.9		2,347.3
Revenue Reserve Payments or Credits		(2,041.8)	(2,701.2)		(2,405.8)
Rebates and Chargebacks [Member] | Sales [Member]
Disaggregation of Revenue [Line Items]
Medicaid lawsuit charge	[2]		(536.0)
Other Sales Deductions [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		9.5	12.3		13.2	$ 17.1
Revenue Reserve Provision		55.2	59.5		68.2
Revenue Reserve Payments or Credits		$ (58.0)	(60.4)		$ (72.1)
Medicaid lawsuit charge			$ 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.