Business (Policies)

3 Months Ended

Mar. 31, 2012

Business [Abstract]

Business Overview

Biogen Idec is a global biotechnology company that discovers, develops, manufactures and markets therapies for the treatment of neurodegenerative diseases, hemophilia and autoimmune disorders. Patients worldwide benefit from our multiple sclerosis therapies.

Basis of presentation

In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair statement of our financial statements for interim periods in accordance with accounting principles generally accepted in the United States (U.S. GAAP). The information included in this quarterly report on Form 10-Q should be read in conjunction with our consolidated financial statements and the accompanying notes included in our Annual Report on Form 10-K for the year ended December 31, 2011 (2011 Form 10-K). Our accounting policies are described in the “Notes to Consolidated Financial Statements” in our 2011 Form 10-K and updated, as necessary, in this Form 10-Q. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three months ended March 31, 2012 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period. Certain prior-year amounts may be reclassified to conform to the current year’s presentation.

Consolidation

Our condensed consolidated financial statements reflect our financial statements, those of our wholly-owned subsidiaries and those of certain variable interest entities in which we are the primary beneficiary. For consolidated entities in which we own or are exposed to less than 100% of the economics, we record net income (loss) attributable to noncontrolling interests in our condensed consolidated statements of income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. All material intercompany balances and transactions are eliminated in consolidation.

In determining whether we are the primary beneficiary of an entity, we apply a qualitative approach that determines whether we have both (1) the power to direct the economically significant activities of the entity and (2) the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. These considerations impact the way we account for our existing collaborative relationships and determine whether we consolidate companies or entities with which we have collaborative or other arrangements. Determination about whether an enterprise should consolidate a variable interest entity is required to be made continuously as changes to existing relationships or future transactions may result in us consolidating or deconsolidating our partner(s) to collaborations and other arrangements.

Use of Estimates

The preparation of our condensed consolidated financial statements in accordance with U.S. GAAP requires management to make estimates, judgments, and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. On an on-going basis, we evaluate our estimates and judgments and methodologies, including those related to revenue recognition and related allowances, our collaborative relationships, clinical trial expenses, the consolidation of variable interest entities, the valuation of contingent consideration, the valuation of acquired intangible assets including in-process research and development, inventory, impairment and amortization of long-lived assets including intangible assets, impairments of goodwill, share-based compensation, income taxes including the valuation allowance for deferred tax assets, the valuation of investments, derivatives and hedging activities, contingencies, litigation, and restructuring charges. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions.