Equity

9 Months Ended

Sep. 30, 2013

Equity [Abstract]

Equity

Equity

Total equity as of September 30, 2013 increased $1,161.9 million compared to December 31, 2012. This increase was primarily driven by net income attributable to Biogen Idec Inc. of $1,405.0 million and an increase in additional paid in capital resulting from our share-based compensation arrangements totaling $132.9 million, partially offset by repurchases of our common stock totaling $400.3 million.

Share Repurchases

In February 2011, our Board of Directors authorized the repurchase of up to 20.0 million shares of common stock. This authorization does not have an expiration date. During the nine months ended September 30, 2013, we repurchased approximately 2.0 million shares at a cost of $400.3 million. Of those shares, 1.7 million were repurchased during the three months ended September 30, 2013 at a cost of $359.3 million. During the nine months ended September 30, 2012, we repurchased approximately 7.7 million shares at a cost of approximately $963.2 million.

Approximately 4.2 million shares of our common stock remain available for repurchase under the 2011 authorization.

Noncontrolling Interests

The following table reconciles equity attributable to noncontrolling interests:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2013		2012		2013			2012
Noncontrolling interests, beginning of period	$	0.6	$	2.4	$	2.3		$	1.5
Net income attributable to noncontrolling interests, net of tax	—		—		—			—
Currency translation adjustment	—		—		—			0.1
Deconsolidation of noncontrolling interest	—		—		(1.7		)	(0.5		)
Distributions to noncontrolling interests	—		—		—			1.3
Noncontrolling interests, end of period	$	0.6	$	2.4	$	0.6		$	2.4

For additional information related to our deconsolidation of noncontrolling interests related to Knopp Neurosciences, Inc. in March 2013, please read Note 18, Investments in Variable Interest Entities to these condensed consolidated financial statements.