Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Dec. 26, 2014	Jun. 26, 2020	Jun. 28, 2019	Dec. 27, 2019
Income Taxes [Line Items]
Income tax expense (benefit)	$ 161.3	$ (24.3)		$ 142.4	$ (229.0)
Increase (decrease) tax benefit	(185.6)			371.4
Increase (Decrease) Tax Benefit, Intercompany Financing Reorganization	4.3			197.1
(Loss) income from continuing operations before income taxes	$ (789.3)	$ (24.8)		$ (864.9)	$ (74.3)
Effective tax rate	(20.40%)	98.00%		(16.50%)	308.20%
Current Income Tax Expense (Benefit)	$ 146.5	$ (5.6)		$ 168.8	$ (44.1)
Deferred Income Tax Expense (Benefit)	307.8	$ (29.9)		(311.2)	$ (273.1)
Income Taxes Paid, Net				32.8		$ 30.7
Operating Loss Carryforwards	891.3			891.3
Unrecognized tax benefits	465.0			465.0		398.6
Unrecognized tax benefits, net increase				66.4
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions				40.3
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations				25.3
Unrecognized tax benefits, which if favorably settled would benefit the effective tax rate	197.8			197.8
Interest accrued on unrecognized tax benefits	28.0			28.0		$ 32.9
Unrecognized tax benefits that would impact effective tax rate, upper bound of change	109.3			109.3
Income tax penalties and interest accrued that would impact effective tax rate, upper bound of change	18.7			18.7
Increase (Decrease) Tax Expense (Benefit), Change in Operating Income	11.7			17.7
Increase (Decrease), Tax Expense (Benefit), Gain on Debt Repurchases	(7.2)			(8.9)
Increase (Decrease), Tax Expense (Benefit), Restructuring	0.9			0.5
Increase (Decrease), Tax Expense (Benefit), CARES Act	38.1			49.6
Increase (Decrease), Tax Expense (Benefit), Separation Costs	4.6			3.4
Increase (Decrease), Tax Expense (Benefit), Non-restructuring Impairment Charges	8.5			8.5
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions				51.7
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities				0.3
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	341.6
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	341.6
Opioid-Related Litigation Settlement charge [Member]
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	202.7			202.7
Medicaid Lawsuit [Member]
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	138.9
Nuclear Imaging
Income Taxes [Line Items]
Income tax expense (benefit)	17.3
Unrecognized Tax Benefits, Interest on Income Taxes Expense	$ 18.1
CARES Act [Member]
Income Taxes [Line Items]
Proceeds from Income Tax Refunds				200.5
Income tax expense (benefit)				$ (49.6)
Internal Revenue Service (IRS) [Member] | Cadence Pharmaceuticals, Inc. [Member]
Income Taxes [Line Items]
Proposed Adjustment to Taxable Income			$ 871.0