Equity

9 Months Ended

Sep. 30, 2012

Equity [Abstract]

Equity

Equity

Total equity as of September 30, 2012 increased $235.0 million compared to December 31, 2011. This increase was primarily driven by net income attributable to Biogen Idec Inc. of $1,087.9 million and the increase in additional paid-in capital resulting from our share based compensation arrangements totaling $134.0 million offset by repurchases of our common stock totaling $963.2 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, 2012, approximately 7.7 million shares were repurchased at a cost of $963.2 million. Of those shares, 0.4 million were repurchased and retired during the three months ended September 30, 2012 at a cost of $53.2 million.

Approximately 6.3 million shares of our common stock remain available for repurchase under the 2011 authorization.

We repurchased approximately 5.0 million shares at a cost of approximately $386.6 million under the 2011 authorization during the nine months ended September 30, 2011.

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)	2012		2011			2012			2011
Noncontrolling interests, beginning of period	$	2.4	$	79.1		$	1.5		$	52.9
Net income (loss) attributable to noncontrolling interests, net of tax	—		1.9			—			32.3
Currency translation adjustment	—		(0.8		)	0.1			4.9
Deconsolidation of noncontrolling interest	—		—			(0.5		)	—
Distributions to noncontrolling interests	—		(14.1		)	1.3			(24.0		)
Acquisition of noncontrolling interests	—		(61.7		)	—			(61.7		)
Noncontrolling interests, end of period	$	2.4	$	4.4		$	2.4		$	4.4