Commitments and Contingencies (Narrative) (Details)				3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2018 Defendent	Apr. 01, 2014 USD ($) Defendent	Mar. 19, 2014 USD ($)	Dec. 27, 2019 USD ($)	Sep. 27, 2019 USD ($) Case	Sep. 28, 2018 USD ($)	Sep. 27, 2019 USD ($) lawsuit Case Defendent	Sep. 28, 2018 USD ($)	Sep. 26, 2014 USD ($)	Jul. 18, 2019 USD ($)	Dec. 28, 2018 USD ($)	Aug. 07, 2018 USD ($)	Mar. 25, 2016 USD ($)
Loss Contingencies [Line Items]
Environmental liabilities					$ 62,000,000.0		$ 62,000,000.0
Deferred Tax Liabilities Installment Sales					0		0				$ 227,500,000
Section 453(a) interest								$ 18,100,000
Interest Payable, Installment Sales					47,400,000		47,400,000				$ 56,000,000.0
Decrease, Interest Payable, Installment Sales					8,600,000
Operating Loss Carryforwards					849,300,000		849,300,000
Track 1 Cases [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual, Product Liability, Gross					6,000,000.0		6,000,000.0
Loss Contingency, Accrual, Noncurrent					500,000		$ 500,000
Questcor Subpoena [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements					$ 15,400,000
Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Number of defendants | Defendent		70
Environmental liabilities						$ 26,200,000		$ 26,200,000
Remedial cost, estimate		$ 1,700,000,000											$ 1,380,000,000
Loss Contingency, Settlement Agreement, Amount												$ 280,600
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)						$ (11,800,000)
Occidental, Lower Passaic River [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent	120
Asbestos Matters
Loss Contingencies [Line Items]
Pending claims | Case					11,700		11,700
Estimation of liability, historical term							5 years
Estimation of liability, expected future term of claims							7 years
Accrued and other current liabilities
Loss Contingencies [Line Items]
Environmental liabilities, current					$ 1,700,000		$ 1,700,000
Minimum | Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Remedial cost, estimate					0		0
Minimum | Environmental Remediation
Loss Contingencies [Line Items]
Remedial cost, estimate					36,800,000		36,800,000
Minimum | Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Remedial cost, estimate		365,000,000.0
Maximum | Medicaid Lawsuit [Member]
Loss Contingencies [Line Items]
Remedial cost, estimate					600,000,000.0		600,000,000.0
Maximum | Environmental Remediation
Loss Contingencies [Line Items]
Remedial cost, estimate					77,600,000		$ 77,600,000
Maximum | Lower Passaic River, New Jersey
Loss Contingencies [Line Items]
Remedial cost, estimate		$ 3,200,000,000
Opioid crisis [Member] | Cities, Counties, and/or Other Government-related Persons/Entities [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							2,315
Opioid crisis [Member] | Hospitals, Health Systems, Unions, Health and Welfare Fund or Third-Party Payers [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							207
Opioid crisis [Member] | Individuals [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							104
Opioid crisis [Member] | State Attorney Generals [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							14
Opioid crisis [Member] | U.S. States [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs | lawsuit							224
U.S. House Committee Investigation [Member]
Loss Contingencies [Line Items]
Number of defendants | Defendent							11
Acthar | Humana Inc. [Member]
Loss Contingencies [Line Items]
Proceeds from Customers							$ 700,000,000.0
Cadence Pharmaceuticals, Inc. [Member]
Loss Contingencies [Line Items]
Business Combination, Consideration Transferred			$ 1,329,000,000.0
Silence Therapeutics [Member]
Loss Contingencies [Line Items]
R&D upfront payment					$ 20,000,000.0
Clinical and Regulatory Milestones [Member] | Silence Therapeutics [Member]
Loss Contingencies [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High										$ 10,000,000.0
Commercial Milestones [Member] | Silence Therapeutics [Member]
Loss Contingencies [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High										$ 563,000,000.0
Subsequent Event [Member] | Track 1 Cases [Member]
Loss Contingencies [Line Items]
Payments for Legal Settlements				$ 24,000,000.0
Internal Revenue Service (IRS) [Member] | Cadence Pharmaceuticals, Inc. [Member]
Loss Contingencies [Line Items]
Proposed Adjustment to Taxable Income									$ 871,000,000.0