Fair Value Measurements - Valuation of Financial Instruments Carried at Fair Value (Details) - USD ($)	3 Months Ended	6 Months Ended
	Apr. 02, 2016	Dec. 31, 2015	Mar. 28, 2015	Dec. 27, 2014	Nov. 08, 2013
Assets:
Indefinite-lived intangible assets	$ 1,082,000,000
Liabilities:
Senior notes	5,937,100,000	$ 4,698,300,000			$ 2,300,000,000
Goodwill impairment charge	130,500,000	0
Indefinite-lived intangible assets, carrying value	1,355,400,000
Indefinite-lived intangible assets impairment	273,400,000
BCH
Liabilities:
Goodwill	1,723,800,000
Goodwill impairment charge	130,500,000
Measured on a recurring basis
Assets:
Tysabri® royalty stream - at fair value (restated)	5,020,000,000	5,310,000,000
Measured on a recurring basis | Level 1
Assets:
Investment securities	38,600,000	14,900,000
Measured on a recurring basis | Level 2
Assets:
Foreign currency forward contracts	9,400,000	4,800,000
Funds associated with Israeli post-employment benefits	17,600,000	17,200,000
Total level 2 assets	27,000,000	22,000,000
Liabilities:
Interest rate swap agreements	0	300,000
Foreign currency forward contracts	3,400,000	3,900,000
Total level 2 liabilities	3,400,000	4,200,000
Measured on a recurring basis | Level 3 | Contingent consideration classified as equity
Liabilities:
Contingent consideration	48,000,000	17,900,000	$ 12,400,000	$ 12,400,000
Measured on a non-recurring basis | Level 3
Assets:
Restated goodwill	1,593,300,000	0
Indefinite-lived intangible assets	1,082,000,000	1,031,800,000
Assets held for sale, net	0	37,500,000
Total level 2 assets	$ 2,675,300,000	$ 1,069,300,000