Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2012

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data (Unaudited)

Quarterly Financial Data (Unaudited)

(In millions, except per share amounts)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total Year
2012	(a)		(b)				(c) (d)
Product revenues	$	975.4	$	1,076.8	$	1,039.1	$	1,074.7	$	4,166.1
Unconsolidated joint business revenues	$	284.6	$	284.6	$	287.8	$	280.9	$	1,137.9
Other revenues	$	32.0	$	59.6	$	58.6	$	62.3	$	212.5
Total revenues	$	1,292.0	$	1,421.0	$	1,385.5	$	1,417.9	$	5,516.5
Gross profit	$	1,158.8	$	1,281.8	$	1,246.2	$	1,284.1	$	4,971.0
Net income	$	302.4	$	387.1	$	398.4	$	292.1	$	1,380.0
Net income attributable to Biogen Idec Inc.	$	302.7	$	386.8	$	398.4	$	292.1	$	1,380.0
Basic earnings per share attributable to Biogen Idec Inc.	$	1.26	$	1.62	$	1.68	$	1.24	$	5.80
Diluted earnings per share attributable to Biogen Idec Inc.	$	1.25	$	1.61	$	1.67	$	1.23	$	5.76

(In millions, except per share amounts)	First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total Year
2011			(e)				(f)
Product revenues	$	907.1	$	956.7	$	975.8	$	996.6	$	3,836.1
Unconsolidated joint business revenues	$	256.1	$	216.5	$	266.5	$	257.5	$	996.6
Other revenues	$	40.1	$	35.5	$	67.7	$	72.6	$	215.9
Total revenues	$	1,203.3	$	1,208.6	$	1,309.9	$	1,326.7	$	5,048.6
Gross profit	$	1,100.2	$	1,108.1	$	1,186.4	$	1,187.1	$	4,581.9
Net income	$	308.8	$	304.0	$	353.7	$	300.2	$	1,266.7
Net income attributable to Biogen Idec Inc.	$	294.3	$	288.0	$	351.8	$	300.2	$	1,234.4
Basic earnings per share attributable to Biogen Idec Inc	$	1.22	$	1.19	$	1.45	$	1.24	$	5.09
Diluted earnings per share attributable to Biogen Idec Inc	$	1.20	$	1.18	$	1.43	$	1.22	$	5.04

Full year amounts may not sum due to rounding.

(a) Net income and net income attributable to Biogen Idec Inc. for the first quarter of 2012 includes a charge to research and development expense of $29.0 million related to an upfront payment made in connection with our development agreement entered into with Isis Pharmaceuticals, Inc. and a $12.4 million reduction resulting from an increase in our returns reserve and write-offs of unsold inventory due to a voluntary withdrawal of a limited amount of AVONEX product that has demonstrated a trend in oxidation that may lead to expiry earlier than stated on its label.

(b) Net income and net income attributable to Biogen Idec Inc. for the second quarter of 2012 includes a charge to research and development expense of $12.0 million related to an upfront payment made in connection with our development agreement entered into with Isis Pharmaceuticals, Inc.

(c) Net income and net income attributable to Biogen Idec Inc. for the fourth quarter of 2012 includes the correction of an error that had accumulated over several prior years in our deferred tax accounting for capitalized interest which resulted in an expense of $29.0 million.

(d) Net income and net income attributable to Biogen Idec Inc. for the fourth quarter of 2012 includes a charge to research and development expense of $30.0 million related to an upfront payment made in connection with our development agreement entered into with Isis Pharmaceuticals, Inc.

(e) Our share of RITUXAN revenues from unconsolidated joint business was reduced by approximately $50.0 million in the second quarter of 2011 as a result of an accrual for estimated compensatory damages (including interest) relating to Genentech’s ongoing arbitration with Hoechst GmbH. For additional information related to this matter, please read Note 22, Litigation to these consolidated financial statements.

(f) Net income and net income attributable to Biogen Idec Inc. for the fourth quarter of 2011 includes a charge to research and development expense of $36.8 million related to an upfront payment made in connection with our collaboration and license agreement entered into with Portola Pharmaceuticals, Inc.