Commitments and Contingencies (Narrative) (Details)						3 Months Ended	12 Months Ended
		Jun. 30, 2018 Defendent	Dec. 11, 2017 USD ($)		Mar. 19, 2014 USD ($)	Sep. 28, 2018 USD ($)	Dec. 27, 2019 USD ($) lawsuit Case Defendent	Dec. 28, 2018 USD ($)	Dec. 29, 2017 USD ($)	Sep. 26, 2014 USD ($)	Aug. 07, 2018 USD ($)	Mar. 25, 2016 USD ($)	Apr. 11, 2014 USD ($)
Loss Contingencies [Line Items]
Deferred Tax Liabilities Installment Sales							$ 0	$ 227,500,000
Operating Loss Carryforwards							$ 782,000,000.0
Document Period End Date							Dec. 27, 2019
Environmental liabilities							$ 61,900,000
Interest Expense, Installment Sales								23,700,000	$ 69,300,000
Interest Payable, Installment Sales							47,400,000	56,000,000.0
Installment note deferred asset write off, net									8,400,000
Decrease, Interest Payable, Installment Sales							8,600,000
Track 1 Cases [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements							24,000,000.0
Loss Contingency Accrual, Product Liability, Gross							6,000,000.0
Loss Contingency, Accrual, Noncurrent							$ 500,000
Occidental, Lower Passaic River [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent		120
Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Environmental liabilities						$ 26,200,000
Remedial cost, estimate												$ 1,380,000,000	$ 1,700,000,000
Loss Contingency, Settlement Agreement, Amount											$ 280,600
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)						$ (11,800,000)
Asbestos Matters
Loss Contingencies [Line Items]
Pending claims | Case							11,800
Estimation of liability, historical term							5 years
Estimation of liability, expected future term of claims							7 years
Questcor Subpoena [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements							$ 15,400,000
Marietta, GA Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value							2,000,000.0
Other current liabilities
Loss Contingencies [Line Items]
Environmental liabilities, current							$ 1,900,000
U.S. House Committee Investigation [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent							11
Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Number of defendants | Defendent							70
National Benefit Fund Litigation [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent							30
Cesar Castillo, Inc., Litigation [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent							30
Minimum
Loss Contingencies [Line Items]
Remedial cost, estimate							$ 38,200,000
Minimum | Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Remedial cost, estimate													365,000,000.0
Minimum | Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Remedial cost, estimate							0
Maximum
Loss Contingencies [Line Items]
Remedial cost, estimate							86,900,000
Maximum | Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Remedial cost, estimate													$ 3,200,000,000
Maximum | Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Remedial cost, estimate							630,000,000.0
Cadence Pharmaceuticals, Inc. [Member]
Loss Contingencies [Line Items]
Business Combination, Consideration Transferred					$ 1,329,000,000.0
Mesoblast [Member]
Loss Contingencies [Line Items]
Proceeds from Sale of Available-for-sale Securities, Equity								25,500,000
Marketable Securities, Realized Gain (Loss)								3,400,000
Ocera [Member]
Loss Contingencies [Line Items]
Business Combination, Consideration Transferred			$ 64,400,000	[1]				1,900,000	$ 40,500,000
Contingent consideration	[1]		$ 22,000,000.0
Acthar Gel | Humana Inc. [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value							700,000,000.0
Fair Value, Measurements, Recurring
Loss Contingencies [Line Items]
Contingent consideration							69,300,000	151,400,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Loss Contingencies [Line Items]
Contingent consideration							69,300,000	151,400,000
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Stratatech [Member]
Loss Contingencies [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contingent Liability							29,000,000.0	53,700,000
Fair Value, Measurements, Recurring | MNK-6105 [Member] | Fair Value, Inputs, Level 3 | Ocera [Member]
Loss Contingencies [Line Items]
Contingent consideration							$ 15,800,000	$ 21,500,000
Cities, Counties, and/or Other Government-related Persons/Entities [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							2,496
Hospitals, Health Systems, Unions, Health and Welfare Fund or Third-Party Payers [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							253
Individuals [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							110
Schools and School Boards [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							6
State Attorney Generals [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							17
U.S. States [Member] | opioid crisis [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							234
Internal Revenue Service (IRS) [Member] | Cadence Pharmaceuticals, Inc. [Member]
Loss Contingencies [Line Items]
Proposed Adjustment to Taxable Income										$ 871,000,000.0

[1] $1.9 million of the total consideration, net of cash was paid in fiscal 2018, subsequent to the Company's December 11, 2017 acquisition date.