Accrued expenses on funding commitment related to clinical research.

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- Definition

Commitments And Contingencies.

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- Definition

Cumulative sales level

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No definition available.

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- Definition

Future contingent payment for annual worldwide net sales that exceed $2.0 billion

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No definition available.

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- Definition

Future contingent payment for annual worldwide net sales up to $2.0 billion

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No definition available.

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- Definition

Future contingent payment threshold

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No definition available.

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- Definition

Potential future milestone payments commitment to third party approximately.

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No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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- Definition

Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences and carryforwards, classified as noncurrent.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 4
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-Section 45
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Amount of deferred tax liability attributable to taxable temporary differences classified as current.

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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No definition available.

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- Definition

Amount recognized for uncertainty in income taxes classified as current.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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No definition available.

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

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Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2006	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2013	Apr. 02, 2013
Business Acquisition [Line Items]
Maximum contingent consideration in the form of development and approval milestones	$ 1,100.0	$ 1,100.0
Increase to goodwill		1,267.3	$ 1,026.9
Potential future milestone payments commitment, approximately	4,200.0	4,200.0
Cancellable future commitments	460.0	460.0
Commitments And Contingencies (Textual)
Accrued expenses	40.0	40.0
Liabilities associated with uncertain tax positions	77.3	77.3
Lease rent expense which terminates at various dates through 2028		65.3	68.7	$ 68.6
TYSABRI
Business Acquisition [Line Items]
Future contingent payment for annual worldwide net sales up to $2.0 billion										18.00%
Future contingent payment threshold										$ 2,000.0
Future contingent payment for annual worldwide net sales that exceed $2.0 billion										25.00%
Fumapharm AG
Business Acquisition [Line Items]
Amount paid in cash					$ 220.0
Solothurn
Business Acquisition [Line Items]
Cancellable future commitments	270.0	270.0
TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Maximum contingent consideration in the form of development and approval milestones									$ 15.0
Increase to goodwill		1,500.0	1,200.0
Fourteen billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill		1,200.0
Cumulative sales level						$ 14,000.0
Eleven billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level			$ 11,000.0
Twelve billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level								$ 12,000.0
Thirteen billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level							$ 13,000.0
Fifteen billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level	15,000.0	15,000.0
Sixteen billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill	600.0
Cumulative sales level	16,000.0	16,000.0
One billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level	1,000.0	1,000.0
Each additional one billion up to twenty billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill		300.0
Cumulative sales level	20,000.0	20,000.0
Three billion \| TECFIDERA \| Fumapharm AG
Business Acquisition [Line Items]
Cumulative sales level	3,000.0	3,000.0
Development Milestones [Member]
Business Acquisition [Line Items]
Potential future milestone payments commitment, approximately	700.0	700.0
Regulatory Milestones [Member]
Business Acquisition [Line Items]
Potential future milestone payments commitment, approximately	1,500.0	1,500.0
Commercial Milestones [Member]
Business Acquisition [Line Items]
Potential future milestone payments commitment, approximately	2,000.0	2,000.0
2017 Tax Act
Business Acquisition [Line Items]
Accrued income tax liability under the Transition Toll Tax	989.6	989.6
Accrued income tax liability under the Transition Toll Tax, current	$ 78.3	$ 78.3