Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended		11 Months Ended	12 Months Ended
	Dec. 29, 2023	Dec. 30, 2022	Jun. 16, 2022	Nov. 14, 2023	Dec. 27, 2024	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue Reserves	$ 227.4	$ 294.0	$ 276.9	$ 250.5	$ 228.8	$ 272.8
Revenue Reserve Provision	182.9	848.1	715.7	1,422.0	1,676.0
Capitalized Contract Cost, Gross	0.6				37.8
Revenue Reserve Payments or Credits	206.0	831.0	(711.6)	1,465.5	1,674.6
Net sales	243.0	1,039.7	874.6	1,622.9	1,979.7
Capitalized Contract Cost, Amortization	0.0	$ 1.0	$ 2.9	$ 1.9	2.0
Accrued Medicaid	59.0				26.4
Accrued rebates	35.1				61.4
Acthar Managed Care and Medicare
Disaggregation of Revenue [Line Items]
Accrued rebates	$ 31.8				$ 39.8
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred over Time	14.70%	17.00%	19.20%	16.80%	13.50%
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Transferred at Point in Time	85.30%	83.00%	80.80%	83.20%	86.50%
Royalty [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 0.1	$ 36.2	$ 34.9	$ 4.3	$ 0.1
Sales Returns and Allowances
Disaggregation of Revenue [Line Items]
Revenue Reserves	14.5	16.0	18.6	12.8	14.8	21.5
Revenue Reserve Provision	3.0	7.0	5.2	9.9	20.9
Revenue Reserve Payments or Credits	(1.3)	(9.6)	(8.1)	(13.1)	(20.6)
Rebates and Chargebacks [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	201.6	265.3	250.6	224.0	197.5	241.8
Revenue Reserve Provision	173.0	804.4	693.4	1,368.8	1,598.9
Revenue Reserve Payments or Credits	(195.4)	(789.7)	(684.6)	(1,410.1)	(1,603.0)
Other Sales Deductions [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	11.3	12.7	7.7	13.7	16.5	$ 9.5
Revenue Reserve Provision	6.9	36.7	17.1	43.3	56.2
Revenue Reserve Payments or Credits	$ (9.3)	$ (31.7)	$ (18.9)	$ (42.3)	$ (51.0)