Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 27, 2025	Jun. 28, 2024	Jun. 27, 2025	Jun. 28, 2024	Dec. 27, 2024	Dec. 29, 2023
Disaggregation of Revenue [Line Items]
Revenue Reserves		$ 290.3	$ 249.8	$ 290.3	$ 249.8	$ 228.8	$ 227.4
Revenue Reserve Provision				842.0	869.2
Revenue Reserve Payments or Credits				(780.5)	(846.8)
Net sales		485.1	514.3	905.0	982.1
Accrued Medicaid		24.4		24.4		26.4
Accrued rebates		89.5		89.5		61.4
Capitalized Contract Cost, Gross		45.9		45.9		37.8
Capitalized Contract Cost, Amortization		1.4	$ 0.3	2.9	$ 0.7
Acthar Managed Care and Medicare
Disaggregation of Revenue [Line Items]
Accrued rebates		$ 63.2		$ 63.2		39.8
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue		87.20%	86.90%	86.30%	85.80%
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue		12.80%	13.10%	13.70%	14.20%
Specialty Brands
Disaggregation of Revenue [Line Items]
Net sales		$ 264.3	$ 274.5	$ 471.6	$ 531.8
Rebates and Chargebacks [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	[1]	255.8	223.3	255.8	223.3	197.5	201.6
Revenue Reserve Provision	[1]			804.7	832.7
Revenue Reserve Payments or Credits	[1]			(746.4)	(811.0)
Allowance for Sales Returns [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		16.6	15.9	16.6	15.9	14.8	14.5
Revenue Reserve Provision				6.7	11.0
Revenue Reserve Payments or Credits				(4.9)	(9.6)
Other Sales Deductions [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		$ 17.9	$ 10.6	17.9	10.6	$ 16.5	$ 11.3
Revenue Reserve Provision				30.6	25.5
Revenue Reserve Payments or Credits				$ (29.2)	$ (26.2)

[1] Amounts classified within accrued and other current liabilities in the unaudited condensed consolidated balance sheets are comprised of $24.4 million and $26.4 million of accrued Medicaid and $89.5 million and $61.4 million of accrued rebates, of which $63.2 million and $39.8 million related to Acthar Managed Care and Medicare, as of June 27, 2025 and December 27, 2024, respectively. The change in accrued Medicaid and accrued rebates was reflected within other changes in assets and liabilities within the unaudited condensed consolidated statement of cash flows for the six months ended June 27, 2025.