Segment and Geographical Data (Schedule of Net Sales from External Costumers by Product) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 27, 2019	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 27, 2019	Dec. 28, 2018	Dec. 29, 2017
Segment Reporting Information [Line Items]
Net sales		$ 804.9	$ 743.7	$ 823.3	$ 790.6	$ 834.9	$ 799.9	$ 825.5	$ 755.3	$ 3,162.5	$ 3,215.6	$ 3,221.6
Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										2,423.8	2,496.7	2,352.0
Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										738.7	718.9	869.6
Hydrocodone (API) and hydrocodone-containing tablets | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										76.3	65.9	85.3
Oxycodone (API) and oxycodone-containing tablets | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										74.9	66.1	88.0
Acetaminophen (API) | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										189.9	192.7	185.5
Other controlled substances | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										352.5	343.8	412.0
Acthar Gel | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										952.7	1,110.1	1,195.1
Inomax | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										571.4	542.7	505.2
Ofirmev | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										384.0	341.9	302.5
Therakos | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										246.9	231.2	214.9
Amitiza | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales	[1]									208.5	183.8	0.0
BioVectra Inc [Member] | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales	[2]									40.1	53.1	54.7
Other Products | Operating Segments | Specialty Brands [Member]
Segment Reporting Information [Line Items]
Net sales										20.2	33.9	79.6
Other Products | Operating Segments | Specialty Generics [Member]
Segment Reporting Information [Line Items]
Net sales										$ 45.1	$ 50.4	$ 98.8

[1] Amitiza net sales consist of both product and royalty net sales. Refer to Note 4 for further details on Amitiza's revenues.

[2] In November 2019, the Company completed the sale of BioVectra. Refer to Note 5 for further details.