Segment and Geographical Data (Schedule of Net Sales from External Costumers by Product) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Sep. 30, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 25, 2015	Sep. 25, 2015	Jun. 26, 2015	Mar. 27, 2015	Dec. 26, 2014	Sep. 30, 2016	Sep. 25, 2015	Sep. 26, 2014
Segment Reporting Information [Line Items]
Net sales		$ 887.2	$ 866.6	$ 815.8	$ 811.2	$ 778.8	$ 768.5	$ 709.5	$ 666.3	$ 3,380.8	$ 2,923.1	$ 1,650.3
Operating Segments
Segment Reporting Information [Line Items]
Net sales	[1]									3,325.8	2,874.4	1,612.9
Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										1,025.2	1,251.6	1,199.4
Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										2,300.6	1,622.8	413.5
Hydrocodone (API) and hydrocodone-containing tablets | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										103.5	136.5	209.6
Oxycodone (API) and oxycodone-containing tablets | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										126.2	154.6	155.2
Methylphenidate ER | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										146.5	167.2	99.4
Other controlled substances | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										468.1	572.2	584.5
Other | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										180.9	221.1	150.7
Hemostasis Products | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										42.5	0.0	0.0
Ofirmev | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										284.3	263.0	124.4
Acthar | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										1,160.4	1,037.3	122.9
Therakos Immunotherapy | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										207.6	0.0	0.0
Other | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										131.5	137.3	166.2
Product Concentration Risk | Net Sales Attributable to Products | Inomax
Segment Reporting Information [Line Items]
Net sales										$ 474.3	$ 185.2	$ 0.0

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