Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	6 Months Ended			12 Months Ended
	Dec. 30, 2022		Jun. 16, 2022	Dec. 31, 2021		Dec. 25, 2020		Dec. 27, 2019
Disaggregation of Revenue [Line Items]
Revenue Reserves	$ 294.0		$ 276.9	$ 272.8		$ 235.4		$ 337.4
Revenue Reserve Provision			715.7	2,166.0		2,154.3
Capitalized Contract Cost, Gross	10.3			25.8
Revenue Reserve Payments or Credits			(711.6)	(2,128.6)		(2,792.3)
Net sales (includes retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)	1,039.7		874.6	2,208.8		2,213.4
Capitalized Contract Cost, Amortization	1.0		2.9	6.1		5.5
Medicaid lawsuit charge						(536.0)
Accrued Medicaid	89.3			49.6
Accrued rebates	55.3			30.4
Sales [Member]
Disaggregation of Revenue [Line Items]
Medicaid lawsuit charge	0.0	[1]	0.0	0.0	[1]	(536.0)	[1]
Operating Expense [Member]
Disaggregation of Revenue [Line Items]
Medicaid lawsuit charge	$ 0.0		$ 0.0	$ 0.0		$ (105.1)
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred over Time	17.00%		19.20%	20.60%		21.10%
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred at Point in Time	83.00%		80.80%	79.40%		78.90%
Royalty [Member]
Disaggregation of Revenue [Line Items]
Net sales (includes retrospective one-time charge of $536.0 related to the Medicaid lawsuit for fiscal 2020)	$ 36.2		$ 34.9	$ 102.4		$ 70.3
Sales Returns and Allowances
Disaggregation of Revenue [Line Items]
Revenue Reserves	16.0		18.6	21.5		26.6		28.4
Revenue Reserve Provision	7.0		5.2	23.7		28.9
Revenue Reserve Payments or Credits	(9.6)		(8.1)	(28.8)		(30.7)
Medicaid lawsuit charge						0.0
Rebates and Chargebacks [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	265.3		250.6	241.8		196.5		295.8
Revenue Reserve Provision	804.4		693.4	2,087.1		2,065.9
Revenue Reserve Payments or Credits	(789.7)		(684.6)	(2,041.8)		(2,701.2)
Medicaid lawsuit charge						(536.0)
Other Sales Deductions [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	12.7		7.7	9.5		12.3		$ 13.2
Revenue Reserve Provision	36.7		17.1	55.2		59.5
Revenue Reserve Payments or Credits	$ (31.7)		$ (18.9)	$ (58.0)		(60.4)
Medicaid lawsuit charge						$ 0.0

[1] Specialty Brands net sales for fiscal 2020 (Predecessor) 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 (Predecessor).