Discontinued Operations and Divestitures (Narrative) (Details) - USD ($)		1 Months Ended	3 Months Ended									12 Months Ended
		Dec. 31, 2013	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 30, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 25, 2015	Dec. 29, 2017		Sep. 30, 2016		Sep. 25, 2015		Sep. 26, 2014	Mar. 17, 2017	Jan. 27, 2017	Nov. 27, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-restructuring impairment charges							$ 214,300,000					$ 63,700,000		$ 16,900,000		$ 0
Provision for (benefit from) income taxes							121,700,000				$ 37,300,000	1,709,600,000		255,600,000		129,300,000
Tax (benefit) expense on income (loss) from discontinued operations							15,300,000					5,400,000		43,500,000		47,900,000
Income (loss) from discontinued operations, net of income taxes			$ 1,300,000	$ (600,000)	$ (7,800,000)	$ 370,300,000	23,600,000	$ 5,000,000	$ 22,600,000	$ 19,800,000	$ 107,300,000	363,200,000		154,700,000		88,100,000
Gain on Divestiture							0					56,900,000		0		3,000,000
Non-U.K.							82,000,000					37,700,000		120,500,000		67,300,000
Deferred Foreign Income Tax Expense (Benefit)							(203,200,000)					(1,748,300,000)		(377,100,000)		(196,000,000)
Deferred Income Tax Expense (Benefit)							203,700,000					1,747,700,000		376,400,000		196,800,000
U.K.							0					400,000		300,000		200,000
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal							0					56,900,000		0		3,000,000
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	[1]						(123,000,000)					(219,900,000)	[2]	(249,300,000)	[2]	(152,900,000)	[2]
Nuclear Imaging
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration																				$ 690,000,000
Disposal Group, Including Discontinued Operation, Upfront Consideration																				574,000,000
Income tax expense (benefit)												4,300,000		49,000,000		36,400,000
Tax (benefit) expense on income (loss) from discontinued operations							15,300,000					5,200,000		49,000,000		36,400,000
Other Tax Expense (Benefit)							100,000					200,000		900,000		400,000
Increase (Decrease) in Accrued Liabilities							3,300,000					3,300,000		14,400,000
Non-U.K.							15,800,000					200,000		52,500,000		27,800,000
Deferred Foreign Income Tax Expense (Benefit)							500,000					5,400,000		3,600,000		8,600,000
U.K.														100,000		100,000
Discontinued Operation, Amounts of Material Contingent Liabilities Remaining																				$ 77,000,000
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax							0					362,800,000		0		0
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation												(900,000)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount							4,400,000					800,000		11,700,000	[1],[2]	14,300,000	[1],[2]
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax							38,100,000					8,400,000		110,300,000		108,000,000
Contrast Media and Delivery Systems
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration																					$ 270,000,000
Income tax expense (benefit)							0					0		(2,500,000)		10,800,000
Taxes paid or to be paid in connection with disposition																10,000,000
Tax (benefit) expense on income (loss) from discontinued operations														(2,100,000)
Non-U.K.														900,000		14,900,000
Deferred Foreign Income Tax Expense (Benefit)														(3,400,000)		(4,400,000)
U.K.																0
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax							0					0		95,300,000		0
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation														(400,000)
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax							0					0		(7,400,000)		4,900,000
Mallinckrodt Baker
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations, net of income taxes							$ 600,000					(600,000)		$ 3,000,000		(100,000)
Tastemaker
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for Loss (Gain) on Disposal, Net of Tax																$ 22,500,000
Intrathecal Therapy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Consideration																			$ 203,000,000
Disposal Group, Not Discontinued Operation, Fixed Consideration																			171,000,000
Disposal Group, Not Discontinued Operation, Contingent Consideration																			32,000,000
Disposal Group, Not Discontinued Operation, Upfront Consideration																			17,000,000
Disposal Group, Not Discontinued Operation, Note Receivable Consideration																			154,000,000
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Pre-tax												56,600,000
Disposal Group, Not Discontinued Operation, Other Commitment			$ 6,500,000									6,500,000							$ 7,300,000
Oxymorphone ER
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Productive Assets		$ 4,000,000
Contractually Obligated Future Proceeds from Sale Of Productive Assets		$ 8,000,000
Gain on Divestiture																		$ 11,700,000
Other | Intrathecal Therapy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal												48,700,000
Goodwill [Member] | Intrathecal Therapy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal												$ 49,800,000

[1] Includes the impact of certain recurring valuation allowances for U.K. and non-U.K. jurisdictions.

[2] During fiscal 2015, the Research Credit tax law was extended, with a retroactive effective date of January 1, 2014. As such, fiscal 2015 includes approximately $3.6 million of credit related to the period January 1, 2014 through September 26, 2014.