Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jun. 27, 2015	Jul. 02, 2016		Jun. 27, 2015
Income Statement [Abstract]
Net sales	$ 1,340.5	$ 1,415.2	$ 2,687.8	[1]	$ 2,382.4	[1]
Cost of sales	794.0	814.2	1,608.2		1,412.0
Gross profit	546.5	601.0	1,079.6		970.4
Operating expenses
Distribution	22.5	23.7	44.3		38.4
Research and development	47.0	62.6	92.2		98.0
Selling	171.6	174.9	352.4		223.7
Administration	104.3	140.8	211.8		219.8
Impairment charges	10.5	6.8	414.4		6.8
Restructuring	5.8	(0.1)	11.3		1.0
Total operating expenses	361.7	408.7	1,126.4		587.7
Operating income	184.8	192.3	(46.8)	[1]	382.7	[1]
Tysabri® royalty stream - change in fair value	910.8	69.2	1,115.3		(31.5)
Interest expense, net	57.4	45.9	108.6		89.2
Other expense, net	28.8	15.8	31.3		273.9
Loss on extinguishment of debt	0.0	0.9	0.4		0.9
Income (loss) before income taxes	(812.2)	60.5	(1,302.4)		50.2
Income tax expense (benefit)	(277.9)	82.7	(238.9)		94.7
Net loss	$ (534.3)	$ (22.2)	$ (1,063.5)		$ (44.5)
Loss per share
Basic (in dollars per share)	$ (3.73)	$ (0.15)	$ (7.43)		$ (0.31)
Diluted (in dollars per share)	$ (3.73)	$ (0.15)	$ (7.43)		$ (0.31)
Weighted-average shares outstanding
Basic (in shares)	143.2	146.3	143.2		143.5
Diluted (in shares)	143.2	146.3	143.2		143.5
Dividends declared per share (in dollars per share)	$ 0.145	$ 0.125	$ 0.290		$ 0.25

[1] The BCH segment was created on March 30, 2015 as a result of the Omega acquisition, thus data for the six months ended June 27, 2015 includes only three months of results from operations attributable to Omega.