Segment and Geographical Data (Schedule of Segment Reporting Information by Business Segment) (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
Segment Reporting Information [Line Items]
Net sales	$ 243.0	$ 1,039.7	$ 874.6	$ 1,622.9	$ 1,979.7
Operating income (loss)	(20.2)	(316.7)	(57.8)	(517.4)	90.2
Intangible asset amortization	(16.2)	(318.7)	(281.8)	(449.6)	(80.3)
Restructuring and related charges, net	0.0	(11.1)	(9.6)	(0.9)	(10.5)
Other Asset Impairment Charges	2.6	0.0	0.0	135.9	0.0
Depreciation and amortization	25.8	347.5	321.8	490.3	117.2
Restructuring and related costs, accelerated depreciation	0.0	1.0	0.0	0.8	0.0
Assets	3,733.6				3,302.6
Cost of sales	179.1	991.0	582.0	1,300.5	1,152.6
Gross profit	63.9	48.7	292.6	322.4	827.1
Selling, general and administrative expenses	64.2	268.9	266.3	448.2	566.8
Research and development expenses	15.9	64.2	65.5	97.1	115.7
Liabilities management and separation costs	1.4	21.2	9.0	157.7	43.9
Interest expense	(28.3)	(324.3)	(108.6)	(507.2)	(228.3)
Interest income	0.9	3.9	0.6	14.7	27.0
Gain on divestiture (Note 5)	0.0	0.0	0.0	0.0	754.4
Loss on debt extinguishment, net	0.0	0.0	0.0	0.0	(19.7)
Other (expense) income, net	5.4	10.0	(14.6)	(6.5)	(9.1)
Income (loss) from continuing operations before income taxes	(46.2)	(650.3)	(811.3)	(1,909.1)	614.5
Reorganization items, net	$ (4.0)	(23.2)	$ (630.9)	$ (892.7)	$ 0.0
Change in Estimate, Fresh-Start, Amount recognized		$ 30.0
Financial Designation, Predecessor and Successor	Successor	Predecessor	Predecessor	Predecessor	Successor
Acthar Gel
Segment Reporting Information [Line Items]
Inventory provisions	$ 44.0
Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales	139.8		$ 587.1	$ 949.2	$ 1,083.4
Other Asset Impairment Charges	2.6			50.1
Depreciation and amortization	15.2	$ 320.6	286.9	451.6	72.8
Specialty Brands [Member] | StrataGraft [Member]
Segment Reporting Information [Line Items]
Other Asset Impairment Charges				50.1
Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales	103.2		287.5	673.7	896.3
Other Asset Impairment Charges				85.8
Depreciation and amortization	10.4	21.1	29.7	32.4	43.2
Segment Reporting, Reconciling Item, Corporate Nonsegment
Segment Reporting Information [Line Items]
Restructuring and related charges, net		(11.1)	(6.1)	(0.9)
Cost of sales	1.4	1.3	5.2	11.8	15.7
Selling, general and administrative expenses	19.2	85.9	93.6	158.4	209.0
Research and development expenses	5.2	20.1	19.5	34.2	39.9
Operating Segments
Segment Reporting Information [Line Items]
Net sales		1,039.7
Operating income (loss)	7.0	(177.1)	75.6	(154.4)	398.7
Restructuring and related charges, net					(10.5)
Other Asset Impairment Charges	2.6		3.5	135.9
Cost of sales	177.7	989.7	576.8	1,288.7	1,136.9
Selling, general and administrative expenses	45.0	183.0	172.7	289.8	357.8
Research and development expenses	10.7	44.1	46.0	62.9	75.8
Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales	139.8	682.4	587.1	949.2	1,083.4
Operating income (loss)	11.6	(152.3)	43.6	(192.0)	228.4
Restructuring and related charges, net					(10.5)
Other Asset Impairment Charges	2.6		0.0	50.1
Cost of sales	83.6	662.8	371.9	836.1	529.0
Selling, general and administrative expenses	35.2	140.4	137.7	214.6	266.1
Research and development expenses	6.8	31.5	33.9	40.4	49.4
Operating Segments | Specialty Brands [Member] | Acthar Gel
Segment Reporting Information [Line Items]
Net sales	57.0	294.1	221.9	368.3	485.7
Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales	103.2	357.3	287.5	673.7	896.3
Operating income (loss)	(4.6)	(24.8)	32.0	37.6	170.3
Restructuring and related charges, net					0.0
Other Asset Impairment Charges	0.0		3.5	85.8
Cost of sales	94.1	326.9	204.9	452.6	607.9
Selling, general and administrative expenses	9.8	42.6	35.0	75.2	91.7
Research and development expenses	$ 3.9	$ 12.6	$ 12.1	$ 22.5	$ 26.4