Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016		Sep. 26, 2015
Income Statement [Abstract]
Net sales	$ 1,261.6	$ 1,273.1	$ 3,949.3	[1]	$ 3,655.6	[1]
Cost of sales	777.1	737.9	2,385.2		2,150.0
Gross profit	484.5	535.2	1,564.1		1,505.6
Operating expenses
Distribution	21.6	24.9	65.9		63.3
Research and development	50.2	41.6	142.5		139.7
Selling	154.6	167.9	506.9		391.6
Administration	105.4	123.3	317.2		343.1
Impairment charges	1,614.4	0.0	2,028.8		6.8
Restructuring	6.6	2.2	17.9		3.1
Total operating expenses	1,952.8	359.9	3,079.2		947.6
Operating income (loss)	(1,468.3)	175.3	(1,515.1)	[1]	558.0	[1]
Tysabri® royalty stream - change in fair value	377.4	(173.8)	1,492.6		(205.4)
Interest expense, net	54.6	43.4	163.2		132.7
Other expense, net	1.0	10.9	32.4		284.8
Loss on extinguishment of debt	0.7	0.0	1.1		0.9
Income (loss) before income taxes	(1,902.0)	294.8	(3,204.4)		345.0
Income tax expense (benefit)	(311.8)	33.9	(550.7)		128.6
Net income (loss)	$ (1,590.2)	$ 260.9	$ (2,653.7)		$ 216.4
Income (loss) per share
Basic (in dollars per share)	$ (11.10)	$ 1.78	$ (18.53)		$ 1.50
Diluted (in dollars per share)	$ (11.10)	$ 1.78	$ (18.53)		$ 1.50
Weighted-average shares outstanding
Basic (in shares)	143.3	146.3	143.2		144.4
Diluted (in shares)	143.3	146.9	143.2		145.0
Dividends declared per share (in dollars per share)	$ 0.145	$ 0.125	$ 0.435		$ 0.375

[1] The BCH segment was created on March 30, 2015 as a result of the Omega acquisition, thus data for the nine months ended September 26, 2015 includes only six months of results from operations attributable to Omega.