Fair Value Measurements - Financial Instruments at Fair Value (Details) - USD ($)	3 Months Ended				6 Months Ended		12 Months Ended			15 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Apr. 02, 2016	Dec. 31, 2015	Oct. 03, 2016	Dec. 31, 2015	Dec. 31, 2016	Jun. 27, 2015	Jun. 28, 2014	Oct. 01, 2016	Apr. 04, 2016
Assets:
Indefinite-lived intangible assets					$ 674,200,000						$ 364,500,000
Definite lived asset impairment						$ 185,100,000	$ 665,600,000	$ 0	$ 0
Finite-Lived Intangible Assets, Gross	$ 4,417,200,000			$ 3,705,300,000		3,705,300,000	4,417,200,000	3,354,000,000
Liabilities:
Goodwill impairment charge	224,100,000	$ 737,900,000	$ 130,500,000			0	1,092,500,000		0
Definite-lived intangible assets, fair value	114,500,000			1,916,300,000		1,916,300,000	114,500,000	2,263,100,000
Impairment charges, indefinite-lived intangible assets					$ 849,100,000		849,500,000
Recurring | Level 1
Assets:
Investment securities	38,200,000			14,900,000		14,900,000	38,200,000	12,700,000
Recurring | Level 2
Assets:
Foreign currency forward contracts	3,800,000			4,800,000		4,800,000	3,800,000	12,400,000
Funds associated with Israeli severance liability	15,900,000			17,200,000		17,200,000	15,900,000	17,300,000
Total assets	19,700,000			22,000,000		22,000,000	19,700,000	29,700,000
Liabilities:
Interest rate swap agreements	0			300,000		300,000	0	0
Foreign currency forward contracts	5,000,000			3,900,000		3,900,000	5,000,000	4,600,000
Total liabilities	5,000,000			4,200,000		4,200,000	5,000,000	4,600,000
Recurring | Level 3
Assets:
Tysabri® royalty stream - at fair value (restated)	2,350,000,000			5,310,000,000		5,310,000,000	2,350,000,000	5,420,000,000
Nonrecurring | Level 3
Assets:
Goodwill	1,148,400,000			0		0	1,148,400,000	0
Indefinite-lived intangible assets	300,000			1,031,800,000		1,031,800,000	300,000	0
Definite-lived intangible assets	758,000,000			0		0	758,000,000	0
Assets held for sale, net	18,200,000			37,500,000		37,500,000	18,200,000	0
Total assets	1,924,900,000			1,069,300,000		1,069,300,000	1,924,900,000	0
Contingent consideration | Recurring | Level 3
Liabilities:
Contingent consideration	69,900,000			17,900,000		17,900,000	69,900,000	0	$ 17,400,000
Omega Restated | Brands
Assets:
Definite lived asset impairment						$ 185,100,000	1,500,000,000			$ 290,900,000
Liabilities:
Impairment charges, indefinite-lived intangible assets		$ 575,700,000	$ 273,400,000	$ 185,100,000			400,000
CHCI
Assets:
Finite-Lived Intangible Assets, Gross	2,300,000,000						2,300,000,000
Liabilities:
Goodwill, gross	2,200,000,000						2,200,000,000
Goodwill impairment charge							868,400,000	$ 0
Indefinite-lived intangible assets, carrying value	$ 700,000						$ 700,000