Goodwill and Intangible Assets Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Sep. 30, 2022	Dec. 30, 2022	Jun. 16, 2022	Dec. 31, 2021	Dec. 25, 2020	Sep. 14, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible asset amortization		$ 318.7	$ 281.8	$ 581.1	$ 771.2
Finite-Lived Intangible Assets [Line Items]
Other Asset Impairment Charges		0.0	0.0	154.9	63.5
Indefinite-lived intangible assets, gross		121.3	233.3	116.0
Intangible Assets, Net (Excluding Goodwill)		2,843.8		5,448.4
Intangible Assets, Gross (Excluding Goodwill)			3,152.2
Intangible asset amortization		$ 318.7	$ 281.8	$ 581.1	$ 771.2
Loss from continuing operations		$ (45.43)	$ (3.70)	$ (8.54)	$ (11.48)
Finite-lived intangible assets, gross		$ 3,041.2	$ 2,918.9	$ 10,601.8
Completed Technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross		3,041.2		10,404.0
Reorganization, Chapter11, Post Adjustment, Successor
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)			3,152.2
Amitiza
Finite-Lived Intangible Assets [Line Items]
Other Asset Impairment Charges				90.4
MNK-6105 [Member]
Finite-Lived Intangible Assets [Line Items]
Other Asset Impairment Charges				$ 64.5
Terlipressin [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross			104.8			$ 104.8
StrataGraft [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross			56.8
StrataGraft PRV
Finite-Lived Intangible Assets [Line Items]
Other Indefinite-lived Intangible Assets			100.0
StrataGraft PRV | Mallinckrodt
Finite-Lived Intangible Assets [Line Items]
Proceeds from Sale of Intangible Assets	$ 65.0	65.0
StrataGraft PRV | General Unsecured Claims Trust
Finite-Lived Intangible Assets [Line Items]
Proceeds from Sale of Intangible Assets	$ 35.0	$ 35.0
Amitiza
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross			84.5
Amitiza | Change in Accounting Method Accounted for as Change in Estimate
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible asset amortization			21.7
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization			$ 21.7
Loss from continuing operations			$ 0.26
Terlivaz | Completed Technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross						$ 17.5