Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
	Mar. 19, 2014	Sep. 25, 2020	Jun. 26, 2020	Mar. 27, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019	Dec. 27, 2019
Income Taxes [Line Items]
Income tax benefit		$ (211.6)			$ (27.6)	$ (69.2)	$ (256.6)
Increase (decrease) tax benefit		184.0				187.4
Increase (Decrease) Tax Benefit, Intercompany Financing Reorganization		32.0				229.1
(Loss) income from continuing operations before income taxes		$ (19.8)			$ (28.5)	$ (884.7)	$ (102.8)
Effective tax rate		1068.70%			96.80%	7.80%	249.60%
Current Income Tax Expense (Benefit)		$ 201.4			$ (3.3)	$ 370.3	$ (47.4)
Deferred Income Tax Expense (Benefit)		10.2			$ (30.9)	(301.1)	(304.0)
Income Taxes Paid, Net				$ 30.7		42.9
Unrecognized tax benefits		336.9				336.9		$ 398.6
Unrecognized tax benefits, net increase						(61.7)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations		35.7
Unrecognized tax benefits, which if favorably settled would benefit the effective tax rate		77.0				77.0
Interest accrued on unrecognized tax benefits		15.7				15.7		$ 32.9
Unrecognized tax benefits that would impact effective tax rate, upper bound of change		25.0				25.0
Income tax penalties and interest accrued that would impact effective tax rate, upper bound of change		6.0				6.0
Increase (Decrease) Tax Expense (Benefit), Change in Operating Income		12.3				30.0
Increase (Decrease), Tax Expense (Benefit), Gain on Debt Repurchases		(1.2)				(10.1)
Increase (Decrease), Tax Expense (Benefit), Restructuring		2.1				2.6
Increase (Decrease), Tax Expense (Benefit), CARES Act		235.7				285.3
Increase (Decrease), Tax Expense (Benefit), Separation Costs		6.5				9.9
Increase (Decrease), Tax Expense (Benefit), Non-restructuring Impairment Charges						8.5
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions		58.6
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities						80.3
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			$ 341.6
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions						4.3
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
Cadence Pharmaceuticals, Inc. [Member]
Income Taxes [Line Items]
Business Combination, Consideration Transferred	$ 1,329.0
Increase (Decrease), Taxable Income						356.5
Income Tax Examination, Penalties and Interest Expense						11.8
Nuclear Imaging
Income Taxes [Line Items]
Income tax 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						201.0	$ 117.4
Income tax benefit						(285.3)
Current Income Tax Expense (Benefit)		(234.7)
2020 Intercompany Financing and Legal Reorganization [Member]
Income Taxes [Line Items]
Current Income Tax Expense (Benefit)		44.2
Deferred Income Tax Expense (Benefit)		(12.2)
Deferred Tax Assets, Tax Deferred Expense		$ 312.2				$ 312.2