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Schedule Of Development Milestone And Collaboration.

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Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

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Amount of Net Income (Loss) attributable to noncontrolling interest.

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The costs incurred in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, excluding in-process research and development acquired in a business combination consummated during the period. Excludes software research and development, which has a separate concept.

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- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount of accelerated depreciation charged against earnings associated with exit from or disposal of business activities or restructuring plan.

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Quarterly Financial Data (Unaudited) (Details Textual) - USD ($) $ in Millions	3 Months Ended							12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Development Milestone And Collaboration [Line Items]
Restructuring charges								$ 33.1	$ 93.4	$ 0.0
Research and development								1,973.3	2,012.8	1,893.4
TECFIDERA litigation settlement and license charges								454.8	0.0	0.0
Net (loss) income attributable to noncontrolling interests, net of tax								(7.1)	46.2	$ 6.8
Eisai
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development							$ 21.6	50.0
AGTC
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development						$ 48.1		26.5	$ 54.5
Mitsubishi Tanabe Pharma Corporation
Schedule Of Development Milestone And Collaboration [Line Items]
Research and development					$ 60.0			22.8
Neurimmune
Schedule Of Development Milestone And Collaboration [Line Items]
Net (loss) income attributable to noncontrolling interests, net of tax						$ 60.0
2015 Restructuring Charges
Schedule Of Development Milestone And Collaboration [Line Items]
Restructuring charges				$ 9.7	$ 93.4			8.0
Cambridge, MA
Schedule Of Development Milestone And Collaboration [Line Items]
Accelerated depreciation	$ 14.0	$ 15.7	$ 15.8					$ 45.5
SPINRAZA \| Ionis Pharmaceuticals, Inc. [Member]
Schedule Of Development Milestone And Collaboration [Line Items]
License Fee		$ 75.0