Financial Instruments and Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 27, 2019	Jul. 24, 2019	Dec. 28, 2018	Apr. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent Consideration, Liability, Current	$ 48.2
Contingent Consideration, Liability, Noncurrent	$ 57.2
Silence Therapeutics [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Equity Securities, FV-NI		$ 5.0
Senior Notes | 4.75% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	4.75%			4.75%
Senior Notes | 5.75% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.75%
Senior Notes | 4.88% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	4.875%
Senior Notes | 5.50% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.50%
Unsecured Debt | 5.625% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.625%
Level 3 | Other current and non-current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash surrender value of life insurance	$ 66.8		$ 66.4
Level 3 | Recurring | Questcor Pharmaceuticals, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of contingent liability	53.7		76.2
Level 3 | StrataGraft [Member] | Recurring | Stratatech
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of contingent liability	35.1		53.7
Level 3 | MNK-6105 [Member] | Recurring | Ocera [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of contingent consideration	$ 16.6		21.5
Level 2 | Debentures | 8.00% Debenture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	8.00%
Level 2 | Debentures | 9.50% Debenture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	9.50%
Level 1 | Senior Notes | 4.75% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	4.75%
Level 1 | Senior Notes | 5.75% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.75%
Level 1 | Senior Notes | 4.88% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	4.875%
Level 1 | Senior Notes | 5.50% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.50%
Level 1 | Unsecured Debt | 5.625% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Stated interest rate	5.625%
Maximum | Synacthen | Questcor Pharmaceuticals, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Milestone Payment	$ 90.0
Nuclear Imaging | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent Consideration, Equity Certificates	18.9		9.0
Indemnification Agreement | Mallinckrodt Baker | Level 1 | Other current and non-current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Restricted Cash and Cash Equivalents	28.0		18.6
Novartis 2015 and 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Business Combination, Contingent Consideration, Annual Payments	25.0
Contingent Liabilities | Level 3 | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value adjustment	23.5
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	$ 105.4		$ 151.4