Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 28, 2025	Mar. 29, 2024	Dec. 27, 2024	Dec. 29, 2023
Disaggregation of Revenue [Line Items]
Revenue Reserves		$ 254.0	$ 230.8	$ 228.8	$ 227.4
Revenue Reserve Provision		399.2	419.6
Revenue Reserve Payments or Credits		(374.0)	(416.2)
Net sales		419.9	467.8
Accrued Medicaid		25.2		26.4
Accrued rebates		55.2		61.4
Capitalized Contract Cost, Gross		44.7		37.8
Capitalized Contract Cost, Amortization		1.5	$ 0.4
Acthar Managed Care and Medicare
Disaggregation of Revenue [Line Items]
Accrued rebates		$ 49.4		39.8
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue		85.10%	84.70%
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue		14.90%	15.30%
Specialty Brands
Disaggregation of Revenue [Line Items]
Net sales		$ 207.3	$ 257.3
Rebates and Chargebacks [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves	[1]	216.3	205.8	197.5	201.6
Revenue Reserve Provision	[1]	379.9	401.2
Revenue Reserve Payments or Credits	[1]	(361.1)	(397.0)
Allowance for Sales Returns [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		16.1	13.0	14.8	14.5
Revenue Reserve Provision		2.1	4.2
Revenue Reserve Payments or Credits		(0.8)	(5.7)
Other Sales Deductions [Member]
Disaggregation of Revenue [Line Items]
Revenue Reserves		21.6	12.0	$ 16.5	$ 11.3
Revenue Reserve Provision		17.2	14.2
Revenue Reserve Payments or Credits		$ (12.1)	$ (13.5)

[1] Amounts classified within accrued and other current liabilities in the unaudited condensed consolidated balance sheets are comprised of $25.2 million and $26.4 million of accrued Medicaid and $55.2 million and $61.4 million of accrued rebates, of which $49.4 million and $39.8 million related to Acthar Managed Care and Medicare, as of March 28, 2025 and December 27, 2024, respectively.