Equity

3 Months Ended

Mar. 31, 2014

Equity [Abstract]

Equity

Equity

Total equity as of March 31, 2014 increased $520.2 million compared to December 31, 2013. This increase was primarily driven by net income attributable to Biogen Idec Inc. of $480.0 million and an increase in additional paid in capital resulting from our share-based compensation arrangements totaling $31.1 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 three months ended March 31, 2014, we did not repurchase any shares of common stock. During the three months ended March 31, 2013, we repurchased approximately 0.3 million shares of common stock at a cost of approximately $41.0 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 (NCI):

	For the Three Months Ended March 31,
(In millions)	2014			2013
Noncontrolling interests, beginning of period	$	0.6		$	2.3
Net income (loss) attributable to noncontrolling interests, net of tax	(0.2		)	—
Fair value of net assets and liabilities acquired and assigned to NCI	4.0			—
Deconsolidation of noncontrolling interest	—			(1.7		)
Noncontrolling interests, end of period	$	4.4		$	0.6