Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions		3 Months Ended		15 Months Ended
	Mar. 30, 2015	Apr. 02, 2016	Mar. 28, 2015	Apr. 02, 2016	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss		$ (529.2)	$ (22.2)
Foreign currency translation adjustments		(151.4)	27.9
Non-current deferred income taxes		1,240.7		$ 1,240.7		$ 1,372.7
Restated Omega
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Acquisition date	Mar. 30, 2015
Adjustments | Tysabri Royalty Stream Fair Value Option Adjustments and Other Misstatements
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss		(194.6)	$ (72.7)
Foreign currency translation adjustments		$ (0.5)
Cumulative effect on retained earnings				$ 41.7
Adjustments | Tax Basis Intangible Assets Misstatement
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Non-current deferred income taxes					$ (236.3)