Debt - Additional Information (Details) $ in Millions				3 Months Ended		9 Months Ended
	Aug. 01, 2025 USD ($)	Jul. 31, 2025 USD ($) Rate	Dec. 06, 2024 USD ($)	Sep. 26, 2025 USD ($)	Sep. 27, 2024 USD ($)	Sep. 26, 2025 USD ($)	Sep. 27, 2024 USD ($)	Dec. 27, 2024 USD ($)	Apr. 23, 2024 USD ($)	Nov. 14, 2023 USD ($) Rate
Debt Instrument
Total debt, principal				$ 3,685.0		$ 3,685.0		$ 865.6
Gain (loss) on debt extinguishment	$ 4.6			4.6	$ 0.0	4.6	$ 0.0
Mallinckrodt & Endo Merger
Debt Instrument
Payment for makewhole premium	24.3
Gain on unamortized premium write off	40.2
Debt fee	11.3
Takeback Term Loans
Debt Instrument
Total debt, principal										$ 871.4
Payment for makewhole premium			$ 63.7
Gain (loss) on debt extinguishment			(19.7)
Gain on unamortized premium write off			44.0
Takeback Term Loans | Redemption period one
Debt Instrument
Repayments of debt			474.1
Payment for makewhole premium			36.4
Takeback Term Loans | Redemption period two
Debt Instrument
Repayments of debt			301.4
Payment for makewhole premium			27.3
First-Out Takeback Term Loan Due November 2028
Debt Instrument
Total debt, principal										229.4
First-Out Takeback Term Loan Due November 2028 | Redemption period one
Debt Instrument
Repayments of debt			227.1
Payment for makewhole premium			15.2
Second-Out Takeback Term Loan Due November 2028
Debt Instrument
Total debt, principal										642.0
Payment for makewhole premium			21.2
Second-Out Takeback Term Loan Due November 2028 | Mallinckrodt & Endo Merger
Debt Instrument
Repayments of debt	385.5
Payment for makewhole premium	10.6
Second-Out Takeback Term Loan Due November 2028 | Redemption period one
Debt Instrument
Repayments of debt			$ 247.0
14.75% Second-Out Takeback Notes
Debt Instrument
Total debt, principal										$ 778.6
Interest rate percentage | Rate										14.75%
14.75% Second Out Takeback Notes | Mallinckrodt & Endo Merger
Debt Instrument
Repayments of debt	477.2
Payment for makewhole premium	$ 13.7
New Credit Agreement
Debt Instrument
Debt fee				$ 28.3		$ 28.3
Debt premium amortization term				5 years		5 years
New Credit Agreement | Long-Term Debt
Debt Instrument
Debt fee				$ 26.8		$ 26.8
New Credit Agreement | Mallinckrodt & Endo Merger
Debt Instrument
New credit agreement, amount		$ 1,350.0
Senior Secured Term Loan Facility | Mallinckrodt & Endo Merger
Debt Instrument
Debt fee		0.0
Senior secured term loan		$ 1,200.0
Prepayment percentage		0.75
Senior Secured Term Loan Facility | Mallinckrodt & Endo Merger | Debt Covenant One
Debt Instrument
Prepayment percentage, covenant		0.50
Debt premium percentage | Rate		2.00%
Senior Secured Term Loan Facility | Mallinckrodt & Endo Merger | Debt Covenant Two
Debt Instrument
Prepayment percentage, covenant		0.25
Maximum leverage ratio, covenant		1.90
Minimum leverage ratio, covenant		1.40
Debt premium percentage | Rate		1.00%
Senior Secured Term Loan Facility | Mallinckrodt & Endo Merger | Debt Covenant Three
Debt Instrument
Prepayment percentage, covenant		1
Maximum leverage ratio, covenant		1.40
6.25% Term Loan Facility | Mallinckrodt & Endo Merger
Debt Instrument
Interest rate percentage | Rate		0.625%
1.25% Term Loan Facility | Mallinckrodt & Endo Merger
Debt Instrument
Interest rate percentage | Rate		1.25%
1.875% Term Loan Facility | Mallinckrodt & Endo Merger
Debt Instrument
Interest rate percentage | Rate		1.875%
2.50% Term Loan Facility | Mallinckrodt & Endo Merger
Debt Instrument
Interest rate percentage | Rate		2.50%
Term Loan due July 2030
Debt Instrument
Principal amount outstanding				1,200.0		1,200.0
Term Loan due April 2031
Debt Instrument
Principal amount outstanding		$ 1,489.0		1,485.0		1,485.0
Remaining borrowing capacity				$ 396.0		$ 396.0
Term Loan due April 2031 | Minimum
Debt Instrument
Interest rate percentage									0.50%
Term Loan due April 2031 | Minimum | SOFR
Debt Instrument
Basis spread on variable rate						3.75%
Term Loan due April 2031 | Minimum | Alternate base rate
Debt Instrument
Basis spread on variable rate						2.75%
Term Loan due April 2031 | Maximum | SOFR
Debt Instrument
Basis spread on variable rate						4.00%
Term Loan due April 2031 | Maximum | Alternate base rate
Debt Instrument
Basis spread on variable rate						3.00%
Revolving Credit Facility due April 2029
Debt Instrument
Maximum leverage ratio, covenant									6.10
Outstanding debt		400.0
Remaining borrowing capacity		$ 396.0
Used capacity									0.40
Maximum capacity covenant									$ 20.0
Revolving Credit Facility due April 2029 | Minimum
Debt Instrument
Interest rate percentage									0.00%
Basis spread on variable rate						0.25%
Revolving Credit Facility due April 2029 | Minimum | SOFR
Debt Instrument
Basis spread on variable rate						3.00%
Revolving Credit Facility due April 2029 | Minimum | Canada prime rate
Debt Instrument
Basis spread on variable rate						2.00%
Revolving Credit Facility due April 2029 | Maximum
Debt Instrument
Basis spread on variable rate						0.50%
Revolving Credit Facility due April 2029 | Maximum | SOFR
Debt Instrument
Basis spread on variable rate						3.50%
Revolving Credit Facility due April 2029 | Maximum | Canada prime rate
Debt Instrument
Basis spread on variable rate						2.50%
8.50% Senior Secured Notes due April 2031
Debt Instrument
Interest rate percentage				8.50%		8.50%			8.50%
Principal amount outstanding				$ 1,000.0		$ 1,000.0
Percentage of principal amount redeemed						100.00%
Redemption price, percentage						1.00%
8.50% Senior Secured Notes due April 2031 | Redemption period one
Debt Instrument
Redemption price, percentage						103.00%
8.50% Senior Secured Notes due April 2031 | Redemption period one | Maximum
Debt Instrument
Percentage of principal amount redeemed						10.00%
8.50% Senior Secured Notes due April 2031 | Redemption period two
Debt Instrument
Redemption price, percentage						108.50%
8.50% Senior Secured Notes due April 2031 | Redemption period two | Maximum
Debt Instrument
Percentage of principal amount redeemed						40.00%
8.50% Senior Secured Notes due April 2031 | Redemption period three
Debt Instrument
Redemption price, percentage						101.00%
8.50% Senior Secured Notes due April 2031 | Redemption period four
Debt Instrument
Redemption price, percentage						104.25%
8.50% Senior Secured Notes due April 2031 | Redemption period five
Debt Instrument
Redemption price, percentage						102.125%
8.50% Senior Secured Notes due April 2031 | Redemption period six
Debt Instrument
Redemption price, percentage						100.00%
Revolving Credit Facility due July 2030
Debt Instrument
Percentage of maximum credit exposure		0.40
Commitment fee percentage		0.25%
Revolving Credit Facility due July 2030 | Other Noncurrent Assets
Debt Instrument
Debt fee				$ 1.5		$ 1.5
Revolving Credit Facility due July 2030 | Debt Covenant One
Debt Instrument
Maximum leverage ratio, covenant		4.00
Revolving Credit Facility due July 2030 | Debt Covenant Two
Debt Instrument
Maximum leverage ratio, covenant		3.25
Revolving Credit Facility due July 2030 | Debt Covenant Three
Debt Instrument
Maximum leverage ratio, covenant		2.50
Revolving Credit Facility due July 2030 | Base Rate
Debt Instrument
Basis spread on variable rate		6.00%
Revolving Credit Facility due July 2030 | SOFR
Debt Instrument
Basis spread on variable rate		7.00%
Revolving Credit Facility due July 2030 | Minimum | Base Rate
Debt Instrument
Interest rate floor		0.0300
Revolving Credit Facility due July 2030 | Minimum | SOFR
Debt Instrument
Interest rate floor		0.0200
Revolving Credit Facility due July 2030 | Mallinckrodt & Endo Merger
Debt Instrument
Senior secured revolving credit facility		$ 150.0