Segment and Geographical Data (Schedule of Segment Reporting Information by Business Segment) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Sep. 25, 2015	Jun. 26, 2015	Mar. 27, 2015	Dec. 26, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 27, 2013	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013
Segment Reporting Information [Line Items]
Net sales		$ 882.4	$ 877.3	$ 819.0	$ 768.2	$ 673.7	$ 530.1	$ 448.7	$ 429.5	$ 3,346.9	$ 2,082.0	$ 1,712.3
Operating income (loss)										461.8	(75.9)	73.5
Intangible asset amortization										(550.3)	(154.8)	(27.9)
Restructuring and related charges, net										(40.7)	(81.9)	(26.3)
Non-restructuring impairment										0.0	151.6	0.0
Separation costs										0.0	(9.6)	(74.2)
Assets		$ 16,404.1				$ 12,787.3				16,404.1	12,787.3
Depreciation and amortization										672.5	275.9	139.6
Restructuring and related costs, accelerated depreciation										0.3	0.5	2.6
Specialty Brands [Member]
Segment Reporting Information [Line Items]
Restructuring and related charges, net										(36.5)	(57.0)	(5.2)
Specialty Generics [Member]
Segment Reporting Information [Line Items]
Restructuring and related charges, net										(4.5)	(9.8)	(11.2)
Operating Segments
Segment Reporting Information [Line Items]
Net sales	[1]									3,298.2	2,044.6	1,655.2
Operating income (loss)										1,339.7	550.1	336.2
Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										1,622.8	413.5	206.4
Operating income (loss)										651.3	(50.6)	(36.2)
Depreciation and amortization	[2]									559.8	152.9	24.9
Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										1,251.6	1,199.4	1,011.2
Operating income (loss)										622.0	617.4	347.9
Depreciation and amortization	[2]									81.9	77.8	72.7
Operating Segments | Global Medical Imaging
Segment Reporting Information [Line Items]
Net sales										423.8	431.7	437.6
Operating income (loss)										66.4	(16.7)	24.5
Depreciation and amortization	[2]									12.4	18.8	18.5
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Net sales	[3],[4]									48.7	37.4	57.1
Corporate and allocated expenses	[5]									(286.9)	(228.1)	(134.3)
Intangible asset amortization										(550.3)	(154.8)	(27.9)
Restructuring and related charges, net	[6]									(40.7)	(81.9)	(26.3)
Non-restructuring impairment										0.0	(151.6)	0.0
Separation costs										0.0	(9.6)	(74.2)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales										0.0	0.0	0.0
Continuing Operations
Segment Reporting Information [Line Items]
Depreciation and amortization	[2]									$ 654.1	$ 249.5	$ 116.1

[1] Amounts represent sales to external customers. There were no intersegment sales.

[2] Depreciation for certain shared facilities is allocated based on occupancy percentage.

[3] Represents historical CMDS-related intercompany transactions that represent Mallinckrodt continuing operations under an ongoing supply agreement with the acquirer of the CMDS business.

[4] Represents historical CMDS-related intercompany transactions that represent Mallinckrodt continuing operations under an ongoing supply agreement with the acquirer of the CMDS business.

[5] Includes administration expenses and certain compensation, environmental and other costs not charged to the Company's operating segments.

[6] Includes restructuring-related accelerated depreciation.