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Income Taxes (Details Textual) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Decrease in unrecognized tax benefits is reasonably possible		$ 25.0
TECFIDERA
Income Tax Contingency [Line Items]
Deferred tax assets, decrease in value	$ 1,700.0
Deferred tax liabilities, decrease in value	$ 1,600.0

X

- Definition

Deferred Tax Assets, Value, Reduction in Value

+ References

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- Definition

Deferred Tax Liabilities, Value, Reduction in Value

+ References

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- Definition

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

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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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