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Earnings per Share (Tables)

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

Basic and diluted earnings per share

Basic and diluted earnings per share are calculated as follows:

	For the Three Months Ended March 31,
(In millions)	2015				2014
Numerator:
Net income attributable to Biogen Inc.	$	822.5			$	480.0
Denominator:
Weighted average number of common shares outstanding	235.0				236.8
Effect of dilutive securities:
Stock options and employee stock purchase plan	0.1				0.1
Time-vested restricted stock units	0.3				0.6
Market stock units	0.2				0.3
Dilutive potential common shares	0.6				1.0
Shares used in calculating diluted earnings per share	235.6				237.8

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- Definition

Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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