Biogen (BIIB) 10-Q 24 Jul 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 17, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	BIOGEN INC.
Entity Central Index Key	875,045
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		235,169,225

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Product, net	$ 2,198,566	$ 2,056,292	$ 4,370,888	$ 3,799,057
Unconsolidated joint business	337,510	303,296	668,121	600,181
Other	55,566	61,864	107,596	151,965
Total revenues	2,591,642	2,421,452	5,146,605	4,551,203
Cost and expenses:
Cost of sales, excluding amortization of acquired intangible assets	286,120	291,887	598,551	571,132
Research and development	490,728	447,273	951,277	976,157
Selling, general and administrative	491,895	576,622	1,052,256	1,088,296
Amortization of acquired intangible assets	92,004	116,826	187,907	260,084
(Gain) loss on fair value remeasurement of contingent consideration	(2,201)	4,019	5,643	3,220
Total cost and expenses	1,358,546	1,436,627	2,795,634	2,898,889
Gain on sale of rights	0	3,900	0	7,759
Income from operations	1,233,096	988,725	2,350,971	1,660,073
Other income (expense), net	(10,889)	4,861	(25,875)	(740)
Income before income tax expense and equity in loss of investee, net of tax	1,222,207	993,586	2,325,096	1,659,333
Income tax expense	292,501	268,521	574,382	446,935
Equity in loss of investee, net of tax	4,881	1,933	5,715	9,538
Net income	924,825	723,132	1,744,999	1,202,860
Net income (loss) attributable to noncontrolling interests, net of tax	(2,451)	8,626	(4,818)	8,398
Net income attributable to Biogen Inc.	$ 927,276	$ 714,506	$ 1,749,817	$ 1,194,462
Net income per share:
Basic earnings per share attributable to Biogen Inc.	$ 3.94	$ 3.02	$ 7.44	$ 5.05
Diluted earnings per share attributable to Biogen Inc.	$ 3.93	$ 3.01	$ 7.42	$ 5.03
Weighted-average shares used in calculating:
Basic earnings per share attributable to Biogen Inc.	235,286	236,661	235,122	236,729
Diluted earnings per share attributable to Biogen Inc.	235,718	237,401	235,671	237,634

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income attributable to Biogen Inc.	$ 927,276	$ 714,506	$ 1,749,817	$ 1,194,462
Other comprehensive income:
Unrealized gains (losses) on securities available for sale, net of tax of $(145) and $(4,029) for the three months ended June 30, 2015 and 2014, respectively; and $621 and $(3,015) for the six months ended June 30, 2015 and 2014, respectively	(214)	(6,865)	1,085	(5,140)
Unrealized gains (losses) on foreign currency forward contracts, net of tax of $(454) and $(260) for the three months ended June 30, 2015 and 2014, respectively; and $(42) and $5 for the six months ended June 30, 2015 and 2014, respectively	(96,159)	10,760	(8,913)	16,551
Unrealized gains (losses) on pension benefit obligation	2,851	(170)	4,109	646
Currency translation adjustment	63,035	(8,047)	(37,818)	(10,991)
Total other comprehensive income (loss), net of tax	(30,487)	(4,322)	(41,537)	1,066
Comprehensive income attributable to Biogen Inc.	896,789	710,184	1,708,280	1,195,528
Comprehensive income (loss) attributable to noncontrolling interests, net of tax	(2,266)	8,626	(4,533)	8,398
Comprehensive income	$ 894,523	$ 718,810	$ 1,703,747	$ 1,203,926

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Tax effect on net unrealized gains (losses) recognized on securities available for sale	$ 145	$ 4,029	$ 621	$ 3,015
Tax effect of net unrealized gains (losses) recognized on foreign currency forward contracts	$ 454	$ 260	$ 42	$ 5

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 1,282,078	$ 1,204,924
Marketable securities	1,086,595	640,460
Accounts receivable, net	1,310,821	1,292,445
Due from unconsolidated joint business, net	323,714	283,360
Inventory	865,738	804,022
Other current assets	750,039	447,462
Total current assets	5,618,985	4,672,673
Marketable securities	2,101,796	1,470,652
Property, plant and equipment, net	1,837,670	1,765,683
Intangible assets, net	4,294,791	4,028,507
Goodwill	2,154,341	1,760,249
Investments and other assets	751,588	618,795
Total assets	16,759,171	14,316,559
Current liabilities:
Current portion of notes payable	3,262	3,136
Taxes payable	457,769	168,058
Accounts payable	282,702	229,178
Accrued expenses and other	1,812,099	1,819,334
Total current liabilities	2,555,832	2,219,706
Notes payable	576,207	582,061
Long-term deferred tax liability	138,403	50,656
Other long-term liabilities	915,731	650,096
Total liabilities	$ 4,186,173	$ 3,502,519
Commitments and contingencies
Biogen Idec Inc. shareholders' equity
Preferred stock, par value $0.001 per share	$ 0	$ 0
Common stock, par value $0.0005 per share	129	129
Additional paid-in capital	4,251,443	4,196,156
Accumulated other comprehensive loss	(101,025)	(59,488)
Retained earnings	11,033,736	9,283,919
Treasury stock, at cost	(2,611,706)	(2,611,706)
Total Biogen Inc. shareholders’ equity	12,572,577	10,809,010
Noncontrolling interests	421	5,030
Total equity	12,572,998	10,814,040
Total liabilities and equity	$ 16,759,171	$ 14,316,559

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Common stock, par value	$ 0.0005	$ 0.0005

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 1,744,999	$ 1,202,860
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	292,523	355,102
Share-based compensation	93,677	83,856
Deferred income taxes	(90,647)	(146,506)
Other	(5,808)	(64,213)
Changes in operating assets and liabilities, net:
Accounts receivable	(38,907)	(188,961)
Inventory	(81,294)	(72,689)
Accrued expenses and other current liabilities	(169,929)	(30,299)
Current taxes payable	102,017	31,113
Other changes in operating assets and liabilities, net	(66,374)	(75,044)
Net cash flows provided by operating activities	1,780,257	1,095,219
Cash flows from investing activities:
Proceeds from sales and maturities of marketable securities	975,517	1,317,525
Purchases of marketable securities	(2,045,046)	(1,787,606)
Acquisitions of business, net of cash acquired	(198,798)	0
Purchases of property, plant and equipment	(227,688)	(118,308)
Contingent consideration related to Fumapharm AG acquisition	250,000	25,000
Other	(10,119)	(10,745)
Net cash flows used in investing activities	(1,756,134)	(624,134)
Cash flows from financing activities:
Purchase of treasury stock	(42,193)	(336,905)
Proceeds from issuance of stock for share-based compensation arrangements	34,727	33,477
Excess tax benefit from stock options	69,690	83,940
Other	14,995	12,003
Net cash flows provided by (used in) financing activities	77,219	(207,485)
Net increase in cash and cash equivalents	101,342	263,600
Effect of exchange rate changes on cash and cash equivalents	(24,188)	(2,965)
Cash and cash equivalents, beginning of the period	1,204,924	602,562
Cash and cash equivalents, end of the period	$ 1,282,078	$ 863,197

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of Significant Accounting Policies Business Overview Biogen is a global biopharmaceutical company focused on discovering, developing, manufacturing and delivering therapies for neurological, autoimmune and hematologic disorders. Our principal marketed products include AVONEX, PLEGRIDY, TECFIDERA, TYSABRI, and FAMPYRA for multiple sclerosis (MS), ALPROLIX for hemophilia B and ELOCTATE for hemophilia A. We also collaborate with Genentech, Inc., a wholly-owned member of the Roche Group, on the development and commercialization of RITUXAN for the treatment of non-Hodgkin's lymphoma, chronic lymphocytic leukemia and other conditions and share profits and losses for GAZYVA, which is approved for the treatment of chronic lymphocytic leukemia. 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 presentation 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, 2014 ( 2014 Form 10-K). Our accounting policies are described in the “ Notes to Consolidated Financial Statements ” in our 2014 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 our audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2015 , are not necessarily indicative of the operating results for the full year or for any other subsequent interim period. Consolidation Our condensed consolidated financial statements reflect our financial statements, those of our wholly-owned subsidiaries and those of certain variable interest entities where we are the primary beneficiary. For consolidated entities where 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. Intercompany balances and transactions are eliminated in consolidation. In determining whether we are the primary beneficiary of an entity and therefore required to consolidate, 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 other arrangements. We continuously assess whether we are the primary beneficiary of a variable interest entity as changes to existing relationships or future transactions may result in us consolidating or deconsolidating one or more of our collaborators or partners. We operate as one operating segment, which is focused on discovering, developing, manufacturing and delivering therapies for neurological, autoimmune and hematologic disorders. Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses, and related disclosure of contingent assets and liabilities. On an on-going basis, we evaluate our estimates and judgments and methodologies. 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. Accounts Receivable Our accounts receivable primarily arise from product sales in the U.S. and Europe and mainly represent amounts due from our wholesale distributors, public hospitals and other government entities. Concentrations of credit risk with respect to our accounts receivable, which are typically unsecured, are limited due to the wide variety of customers and markets using our products, as well as their dispersion across many different geographic areas. The majority of our accounts receivable require payment within 30 to 90 days . We monitor the financial performance and credit worthiness of our customers so that we can properly assess and respond to changes in their credit profile. We provide reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are charged or written-off against the reserve. To date, our historical reserves and write-offs of accounts receivable have not been significant. In countries where we have experienced a pattern of payments extending beyond our contractual payment term and we expect to collect receivables greater than one year after the time of sale, we have discounted our receivables and reduced related revenues over the period of time that we estimate those amounts will be paid using the country’s market-based borrowing rate for such period. The related receivables are classified at the time of sale as non-current assets. We accrete interest income on these receivables, which is recognized as a component of other income (expense), net within our condensed consolidated statement of income. Property, Plant and Equipment Property, plant and equipment are recorded at cost, net of accumulated depreciation. Accumulated depreciation on property, plant and equipment was $1,274.2 million and $1,186.4 million as of June 30, 2015 and December 31, 2014 , respectively. New Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed, we do not believe that the impact of recently issued standards that are not yet effective will have a material impact on our financial position or results of operations upon adoption. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. In July 2015, the FASB decided to delay the effective date of the new revenue standard by one year. The new standard will be effective for us on January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. We are currently evaluating the method of adoption and the potential impact that Topic 606 may have on our financial position and results of operations. In June 2014, the FASB issued ASU No. 2014-11, Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosure. The new standard expanded secured borrowing accounting to include repurchase-to-maturity transactions and repurchase financings and set forth new disclosure requirements for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. We adopted this standard on April 1, 2015 and expanded our disclosures presented within Note 7, Financial Instruments to these condensed consolidated financial statements. The adoption of this standard did not have an impact on our financial position or results of operations. In April 2015, the FASB issued ASU No. 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The new standard requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new standard will be effective for us on January 1, 2016. The adoption of this standard is not expected to have an impact on our financial position or results of operations. In April 2015, the FASB issued ASU No. 2015-05, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. Under this standard, if a cloud computing arrangement includes a software license, the software license element of the arrangement should be accounted for consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the arrangement should be accounted for as a service contract. The new standard will be effective for us on January 1, 2016. The adoption of this standard is not expected to have an impact on our financial position or results of operations. In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). The new standard removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. The new standard will be effective for us on January 1, 2016. Early application is permitted. We maintain investments in certain venture capital funds which primarily invest in small, privately-owned, venture-backed biotechnology companies. The value of our investments in these venture capital funds is estimated using the net asset value of the fund and has been included in the fair value hierarchy disclosure as a Level 3 measurement. These venture capital investments are not material to our financial position or results of operations. We have elected to apply this standard as of June 30, 2015 and our investments in venture capital funds will no longer be included in our disclosures reflected within Note 6, Fair Value Measurements to these condensed consolidated financial statements.

Acquisitions Acquisitions

Acquisitions Acquisitions	6 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Acquisitions	Acquisitions Convergence Pharmaceuticals On February 12, 2015, we completed our acquisition of all of the outstanding stock of Convergence Pharmaceuticals (Convergence), a clinical-stage biopharmaceutical company with a focus on developing product candidates for neuropathic pain. Convergence’s lead candidate is its Phase 2 clinical candidate (CNV1014802), which has demonstrated clinical activity in proof-of-concept studies for trigeminal neuralgia (TGN), a chronic orphan disease. Additionally, CNV1014802 has potential applicability in several other neuropathic pain states. The purchase price consisted of a $200.1 million cash payment at closing, plus contingent consideration in the form of development and approval milestones up to a maximum of $450.0 million , of which $350.0 million is associated with the development and approval of CNV1014802 for the treatment of TGN. The acquisition was funded from our existing cash on hand and has been accounted for as the acquisition of a business. In addition to obtaining the rights to CNV1014802 and additional product candidates in preclinical development, we retained the services of key employees of Convergence. In connection with our acquisition of Convergence, we recorded a liability of $274.5 million representing the fair value of the contingent consideration. This amount was estimated through a valuation model that incorporates industry-based probability adjusted assumptions relating to the achievement of these milestones and thus the likelihood of making the contingent payments. This fair value measurement is based upon significant inputs not observable in the market and therefore represents a Level 3 measurement. The purchase price, as adjusted, consisted of the following: (In millions) Cash portion of consideration $ 200.1 Contingent consideration 274.5 Total purchase price $ 474.6 Subsequent changes in the fair value of the contingent consideration obligation will be recognized as adjustments to contingent consideration and reflected within our condensed consolidated statements of income. For additional information related to the fair value of this obligation, please read Note 6, Fair Value Measurements to these condensed consolidated financial statements. We adjusted our preliminary estimate of the fair value of the separately identifiable assets acquired and contingent consideration as of the date of acquisition to reflect revised estimates to our initial clinical development plans, resulting probabilities of success and the timing of certain milestone payments. The primary effects of these revised estimates resulted in an increase in the value of our estimated contingent consideration and goodwill by $36.0 million , respectively, as compared with March 31, 2015. Our revised purchase price allocation is reflected in the chart below. Our purchase price allocation is substantially complete. The following table summarizes the estimated fair values of the separately identifiable assets acquired and liabilities assumed as of February 12, 2015, as adjusted: (In millions) In-process research and development $ 424.6 Other intangible assets 7.6 Goodwill 128.3 Deferred tax liability (84.9 ) Other, net (1.0 ) Total purchase price $ 474.6 Our estimate of the fair value of the IPR&D programs acquired was determined through a probability adjusted cash flow analysis based on probability weighted net cash flows utilizing a discount rate of 11% . This valuation was primarily driven by the value associated with the lead candidate, CNV1014802, which is in development for the treatment of TGN and is expected to be completed no earlier than 2020, at a remaining cost of approximately $145.0 million . The fair value associated with CNV1014802 for the treatment of TGN was $200.0 million . We have recorded additional IPR&D assets related to the use of CNV1014802 in two additional neuropathic pain indications, with a total estimated value of $220.0 million . The remaining cost of development for these two indications is approximately $415.0 million , with an expected completion date of no earlier than 2021. These fair value measurements were based on significant inputs not observable in the market and thus represent Level 3 fair value measurements. We have attributed the goodwill recognized to the Convergence workforce's expertise in chronic pain research and clinical development and to establishing a deferred tax liability for the acquired IPR&D intangible assets which has no tax basis. The goodwill is not tax deductible. Pro forma results of operations would not be materially different as a result of the acquisition of Convergence and therefore are not presented. Subsequent to the acquisition date, our results of operations include the results of operations of Convergence.

Reserves for Discounts and Allo

Reserves for Discounts and Allowances	6 Months Ended
	Jun. 30, 2015
Sales Discounts, Returns and Allowances, Goods [Abstract]
Reserves for discounts and allowances	Reserves for Discounts and Allowances An analysis of the change in reserves for discounts and allowances is summarized as follows: (In millions) Discounts Contractual Adjustments Returns Total Balance, as of December 31, 2014 $ 47.6 $ 387.1 $ 49.1 $ 483.8 Current provisions relating to sales in current year 209.2 854.4 19.1 1,082.7 Adjustments relating to prior years 0.4 (19.8 ) (8.1 ) (27.5 ) Payments/credits relating to sales in current year (158.0 ) (483.9 ) (0.9 ) (642.8 ) Payments/credits relating to sales in prior years (43.3 ) (254.7 ) (7.8 ) (305.8 ) Balance, as of June 30, 2015 $ 55.9 $ 483.1 $ 51.4 $ 590.4 The total reserves above, included in our condensed consolidated balance sheets, are summarized as follows: (In millions) As of As of Reduction of accounts receivable $ 143.9 $ 124.6 Component of accrued expenses and other 446.5 359.2 Total reserves $ 590.4 $ 483.8

Inventory

Inventory	6 Months Ended
	Jun. 30, 2015
Inventory Disclosure [Abstract]
Inventory	Inventory The components of inventory are summarized as follows: (In millions) As of As of Raw materials $ 173.2 $ 128.3 Work in process 516.7 511.5 Finished goods 175.8 164.2 Total inventory $ 865.7 $ 804.0 As of June 30, 2015 , our inventory included $35.8 million associated with our ZINBRYTA and biosimilar programs, which have been capitalized in advance of regulatory approval. As of December 31, 2014 , our inventory included $6.3 million associated with our ZINBRYTA program, which had been capitalized in advance of regulatory approval.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	6 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Intangible Assets and Goodwill Intangible Assets Intangible assets, net of accumulated amortization, impairment charges and adjustments, are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Estimated Life Cost Accumulated Amortization Net Cost Accumulated Amortization Net Out-licensed patents 13-23 years $ 543.3 $ (493.9 ) $ 49.4 $ 543.3 $ (481.7 ) $ 61.6 Developed technology 15-23 years 3,005.3 (2,492.1 ) 513.2 3,005.3 (2,396.8 ) 608.5 In-process research and development Indefinite until commercialization 752.0 — 752.0 314.1 — 314.1 Trademarks and tradenames Indefinite 64.0 — 64.0 64.0 — 64.0 Acquired and in-licensed rights and patents 3-17 years 3,296.7 (380.5 ) 2,916.2 3,280.4 (300.1 ) 2,980.3 Total intangible assets $ 7,661.3 $ (3,366.5 ) $ 4,294.8 $ 7,207.1 $ (3,178.6 ) $ 4,028.5 For the three and six months ended June 30, 2015 , amortization of acquired intangible assets totaled $92.0 million and $187.9 million , respectively, as compared to $116.8 million and $260.1 million , respectively, in the prior year comparative periods. For the three and six months ended June 30, 2015 , compared to the same periods in 2014 , the decrease in amortization of acquired intangible assets was primarily driven by a decrease in AVONEX and TYSABRI revenues during the comparative periods and higher expected lifetime revenues of TYSABRI as discussed below. Amortization of acquired intangible assets during the six months ended June 30, 2014 also includes a $34.7 million impairment charge related to one of our out-licensed patents. Developed Technology Developed technology primarily relates to our AVONEX product, which was recorded in connection with the merger of Biogen, Inc. and IDEC Pharmaceuticals Corporation in 2003. The net book value of this asset as of June 30, 2015 was $504.3 million . In-process Research and Development (IPR&D) IPR&D represents the fair value assigned to research and development assets that we acquire that have not reached technological feasibility at the date of acquisition. Upon commercialization, we will determine the estimated useful life. In connection with our acquisition of Convergence in February 2015, we acquired IPR&D programs with an estimated fair value of $424.6 million . This amount will be adjusted for foreign exchange rate fluctuations. For a more detailed description of this transaction, please read Note 2, Acquisitions to these condensed consolidated financial statements. Acquired and In-licensed Rights and Patents Acquired and in-licensed rights and patents primarily relate to our acquisition of the TYSABRI rights from Elan Corporation plc (Elan). Elan was acquired by Perrigo Company plc (Perrigo) in December 2013. The net book value of this asset as of June 30, 2015 was $2,851.9 million . Estimated Future Amortization of Intangible Assets Our amortization expense is based on the economic consumption of intangible assets. Our most significant intangible assets are related to our AVONEX and TYSABRI products. Annually, during our long-range planning cycle, we perform an analysis of anticipated lifetime revenues of AVONEX and TYSABRI. This analysis is also updated whenever events or changes in circumstances would significantly affect the anticipated lifetime revenues of either product. Our most recent long range planning cycle was updated in the third quarter of 2014. Our analysis included an increase in the expected future product revenues of TYSABRI, resulting in a decrease in the rate of amortization expense as compared to prior quarters. Our analysis also included a decrease in the expected future product revenues of AVONEX. The results of our TYSABRI and AVONEX analyses were impacted by changes in the estimated impact of TECFIDERA, as well as other existing and potential oral and alternative MS formulations, including PLEGRIDY, that may compete with TYSABRI and AVONEX. Based upon this recent analysis, the estimated future amortization for acquired intangible assets is expected to be as follows: (In millions) As of 2015 (remaining six months) $ 185.5 2016 312.5 2017 285.8 2018 281.6 2019 270.6 2020 263.8 Total $ 1,599.8 Goodwill The following table provides a roll forward of the changes in our goodwill balance: (In millions) Balance, as of December 31, 2014 $ 1,760.2 Increase to goodwill 390.0 Other 4.1 Balance, as of June 30, 2015 $ 2,154.3 The increase in goodwill during the six months ended June 30, 2015 was related to a $300.0 million contingent payment achieved (exclusive of a $38.3 million tax benefit) and to be paid to former shareholders of Fumapharm AG or holders of their rights and our acquisition of Convergence. Other includes changes related to foreign exchange. For additional information related to future contingent payments to the former shareholders of Fumapharm AG or holders of their rights, please read Note 18, Commitments and Contingencies to these condensed consolidated financial statements. For additional information related to our acquisition of Convergence, please read Note 2, Acquisitions to these condensed consolidated financial statements. As of June 30, 2015 , we had no accumulated impairment losses related to goodwill.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The tables below present information about our assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value: As of June 30, 2015 (In millions) Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 974.0 $ — $ 974.0 $ — Marketable debt securities: Corporate debt securities 1,198.1 — 1,198.1 — Government securities 1,700.3 — 1,700.3 — Mortgage and other asset backed securities 290.0 — 290.0 — Marketable equity securities 6.8 6.8 — — Derivative contracts 100.5 — 100.5 — Plan assets for deferred compensation 40.7 — 40.7 — Total $ 4,310.4 $ 6.8 $ 4,303.6 $ — Liabilities: Derivative contracts $ 27.7 $ — $ 27.7 $ — Contingent consideration obligations 495.6 — — 495.6 Total $ 523.3 $ — $ 27.7 $ 495.6 As of December 31, 2014 (In millions) Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 716.3 $ — $ 716.3 $ — Marketable debt securities: Corporate debt securities 1,063.0 — 1,063.0 — Government securities 849.8 — 849.8 — Mortgage and other asset backed securities 198.3 — 198.3 — Marketable equity securities 6.9 6.9 — — Derivative contracts 72.7 — 72.7 — Plan assets for deferred compensation 36.9 — 36.9 — Total $ 2,943.9 $ 6.9 $ 2,937.0 $ — Liabilities: Derivative contracts $ 5.4 $ — $ 5.4 $ — Contingent consideration obligations 215.5 — — 215.5 Total $ 220.9 $ — $ 5.4 $ 215.5 There have been no material impairments of our assets measured and carried at fair value during the three and six months ended June 30, 2015 . In addition, there were no changes in valuation techniques or inputs utilized or transfers between fair value measurement levels during the three and six months ended June 30, 2015 . The fair value of Level 2 instruments classified as cash equivalents and marketable debt securities was determined through third party pricing services. For a description of our validation procedures related to prices provided by third party pricing services, refer to Note 1, Summary of Significant Accounting Policies: Fair Value Measurements , to our consolidated financial statements included within our 2014 Form 10-K. For additional information related to our decision to no longer reflect our investments in venture capital funds within the fair value hierarchy, refer to Note 1, Summary of Significant Accounting Policies: New Accounting Pronouncements , to these condensed consolidated financial statements. Debt Instruments The fair and carrying values of our debt instruments, which are Level 2 liabilities, are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Fair Value Carrying Value Fair Value Carrying Value Notes payable to Fumedica $ 10.0 $ 9.4 $ 12.6 $ 11.7 6.875% Senior Notes due March 1, 2018 621.5 570.1 634.6 573.5 Total $ 631.5 $ 579.5 $ 647.2 $ 585.2 The fair value of our notes payable to Fumedica was estimated using market observable inputs, including current interest and foreign currency exchange rates. The fair value of our 6.875% Senior Notes was determined through market, observable, and corroborated sources. For additional information related to our debt instruments, please read Note 12, Indebtedness to our consolidated financial statements included within our 2014 Form 10-K. Contingent Consideration Obligations The following table provides a roll forward of the fair values of our contingent consideration obligations which includes Level 3 measurements: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Fair value, beginning of period $ 461.8 $ 275.1 $ 215.5 $ 280.9 Additions 36.0 — 274.5 — Changes in fair value (2.2 ) 4.0 5.6 3.2 Payments — — — (5.0 ) Fair value, end of period $ 495.6 $ 279.1 $ 495.6 $ 279.1 As of June 30, 2015 and December 31, 2014 , approximately $302.2 million and $200.0 million , respectively, of the fair value of our total contingent consideration obligations were reflected as components of other long-term liabilities within our condensed consolidated balance sheets with the remaining balances reflected as a component of accrued expenses and other. In connection with our acquisition of Convergence, we recorded a liability of $274.5 million , representing the fair value of the contingent consideration. This valuation was based on probability weighted net cash outflow projections of $450.0 million , discounted using a rate of 2% , which is the estimated cost of debt financing for market participants. This liability reflects the revised estimate from the date of acquisition for our initial clinical development plans, resulting probabilities of success and the timing of certain milestone payments. For a more detailed description of this transaction, please read Note 2, Acquisitions to these condensed consolidated financial statements. Acquired IPR&D In connection with our acquisition of Convergence, we also allocated $424.6 million of the total purchase price to acquired IPR&D, which was capitalized as an intangible asset. The amount allocated to acquired IPR&D was based on significant inputs not observable in the market and thus represented a Level 3 fair value measurement. This estimate was also adjusted from our preliminary estimate as of the date of acquisition to reflect revised estimates to our initial clinical development plans, resulting probabilities of success and the timing of certain milestone payments. These assets will be tested for impairment annually until commercialization, after which time the IPR&D will be amortized over its estimated useful life. For a more detailed description of this transaction, please read Note 2, Acquisitions to these condensed consolidated financial statements.

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Financial Instruments Marketable Securities The following tables summarize our marketable debt and equity securities: As of June 30, 2015 (In millions) Fair Value Gross Unrealized Gains Gross Unrealized Losses Amortized Cost Available-for-sale: Corporate debt securities Current $ 375.9 $ 0.1 $ (0.1 ) $ 375.9 Non-current 822.2 0.4 (1.2 ) 823.0 Government securities Current 710.5 0.1 (0.1 ) 710.5 Non-current 989.8 0.9 (0.1 ) 989.0 Mortgage and other asset backed securities Current 0.2 — — 0.2 Non-current 289.8 0.2 (0.3 ) 289.9 Total marketable debt securities $ 3,188.4 $ 1.7 $ (1.8 ) $ 3,188.5 Marketable equity securities, non-current $ 6.8 $ 1.1 $ — $ 5.7 As of December 31, 2014 (In millions) Fair Value Gross Unrealized Gains Gross Unrealized Losses Amortized Cost Available-for-sale: Corporate debt securities Current $ 370.4 $ — $ (0.2 ) $ 370.6 Non-current 692.6 0.2 (1.5 ) 693.9 Government securities Current 269.9 — (0.1 ) 270.0 Non-current 579.9 0.3 (0.4 ) 580.0 Mortgage and other asset backed securities Current 0.2 — — 0.2 Non-current 198.1 0.2 (0.2 ) 198.1 Total marketable debt securities $ 2,111.1 $ 0.7 $ (2.4 ) $ 2,112.8 Marketable equity securities, non-current $ 6.9 $ 1.2 $ (0.2 ) $ 5.9 The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included within cash and cash equivalents on the accompanying condensed consolidated balance sheet: (In millions) As of As of Commercial paper $ 38.8 $ 54.2 Overnight reverse repurchase agreements 185.0 305.0 Money market funds 740.2 321.2 Short-term debt securities 10.0 35.9 Total $ 974.0 $ 716.3 The carrying values of our commercial paper, including accrued interest, overnight reverse repurchase agreements, money market funds and our short-term debt securities approximate fair value due to their short term maturities. Our overnight reverse repurchase agreements are collateralized with agency-guaranteed mortgage securities and represent approximately 1.1% and 2.1% of total assets as of June 30, 2015 and December 31, 2014 , respectively. Summary of Contractual Maturities: Available-for-Sale Securities The estimated fair value and amortized cost of our marketable debt securities available-for-sale by contractual maturity are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Estimated Fair Value Amortized Cost Estimated Fair Value Amortized Cost Due in one year or less $ 1,086.6 $ 1,086.6 $ 640.5 $ 640.8 Due after one year through five years 1,954.4 1,954.5 1,343.7 1,345.2 Due after five years 147.4 147.4 126.9 126.8 Total available-for-sale securities $ 3,188.4 $ 3,188.5 $ 2,111.1 $ 2,112.8 The average maturity of our marketable debt securities available-for-sale as of June 30, 2015 and December 31, 2014 was approximately 17 months and 15 months , respectively. Proceeds from Marketable Debt Securities The proceeds from maturities and sales of marketable debt securities and resulting realized gains and losses are summarized as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Proceeds from maturities and sales $ 601.9 $ 560.1 $ 975.5 $ 1,317.5 Realized gains $ 0.3 $ 0.2 $ 0.5 $ 0.4 Realized losses $ (0.5 ) $ (0.1 ) $ (0.8 ) $ (0.2 ) Strategic Investments As of June 30, 2015 and December 31, 2014 , our strategic investment portfolio was comprised of investments totaling $45.3 million and $47.8 million , respectively, which are included in investments and other assets in our accompanying condensed consolidated balance sheets. Our strategic investment portfolio includes investments in equity securities of certain biotechnology companies and investments in venture capital funds where the underlying investments are in equity securities of biotechnology companies.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Foreign Currency Forward Contracts - Hedging Instruments Due to the global nature of our operations, portions of our revenues are earned in currencies other than the U.S. dollar. The value of revenues measured in U.S. dollars is therefore subject to changes in foreign currency exchange rates. In order to mitigate these changes we use foreign currency forward contracts to lock in exchange rates associated with a portion of our forecasted international revenues. Foreign currency forward contracts in effect as of June 30, 2015 and December 31, 2014 had durations of 1 to 18 months and 1 to 15 months , respectively. These contracts have been designated as cash flow hedges and accordingly, to the extent effective, any unrealized gains or losses on these foreign currency forward contracts are reported in accumulated other comprehensive income (loss) (referred to as AOCI in the tables below). Realized gains and losses for the effective portion of such contracts are recognized in revenue when the sale of product in the currency being hedged is recognized. To the extent ineffective, hedge transaction gains and losses are reported in other income (expense), net. The notional value of foreign currency forward contracts that were entered into to hedge forecasted revenues is summarized as follows: Notional Amount Foreign Currency: (In millions) As of As of Euro $ 1,437.2 $ 1,174.6 Canadian dollar 32.1 56.7 British pound sterling 21.9 34.5 Japanese yen 15.5 16.6 Australian dollar 10.3 19.9 Total foreign currency forward contracts $ 1,517.0 $ 1,302.3 The portion of the fair value of these foreign currency forward contracts that was included in accumulated other comprehensive income (loss) within total equity reflected gains of $63.1 million and $72.1 million as of June 30, 2015 and December 31, 2014 , respectively. We expect all contracts to be settled over the next 18 months and any amounts in accumulated other comprehensive income (loss) to be reported as an adjustment to revenue. We consider the impact of our and our counterparties’ credit risk on the fair value of the contracts as well as the ability of each party to execute its contractual obligations. As of June 30, 2015 and December 31, 2014 , credit risk did not change the fair value of our foreign currency forward contracts. The following table summarizes the effect of derivatives designated as hedging instruments on our condensed consolidated statements of income: For the Three Months Ended June 30, Net Gains/(Losses) Reclassified from AOCI into Operating Income (Effective Portion) Net Gains/(Losses) Recognized into Net Income (Ineffective Portion) Location 2015 2014 Location 2015 2014 Revenue $ 40.4 $ (5.2 ) Other income (expense) $ 1.2 $ (1.0 ) For the Six Months Ended June 30, Net Gains/(Losses) Reclassified from AOCI into Operating Income (Effective Portion) Net Gains/(Losses) Recognized into Net Income (Ineffective Portion) Location 2015 2014 Location 2015 2014 Revenue $ 75.4 $ (10.0 ) Other income (expense) $ 3.4 $ (1.2 ) Foreign Currency Forward Contracts - Other Derivatives We also enter into other foreign currency forward contracts, usually with one month durations, to mitigate the foreign currency risk related to certain balance sheet positions. We have not elected hedge accounting for these transactions. The aggregate notional amount of these outstanding foreign currency contracts was $472.4 million and $365.2 million as of June 30, 2015 and December 31, 2014 , respectively. Net gains of $13.6 million and $3.9 million related to these contracts were recognized as a component of other income (expense), net, for three and six months ended June 30, 2015 , respectively, as compared to net losses of $2.4 million and $3.8 million , respectively, in the prior year comparative periods. Summary of Derivatives While certain of our derivatives are subject to netting arrangements with our counterparties, we do not offset derivative assets and liabilities within our condensed consolidated balance sheets. The following table summarizes the fair value and presentation in our condensed consolidated balance sheets of our outstanding derivatives including those designated as hedging instruments: (In millions) Balance Sheet Location Fair Value As of June 30, 2015 Hedging Instruments: Asset derivatives Other current assets $ 92.8 Liability derivatives Accrued expenses and other $ 9.8 Other long-term liabilities $ 17.2 Other Derivatives: Asset derivatives Other current assets $ 7.7 Liability derivatives Accrued expenses and other $ 0.7 (In millions) Balance Sheet Location Fair Value As of December 31, 2014 Hedging Instruments: Asset derivatives Other current assets $ 69.5 Investments and other assets $ 1.9 Other Derivatives: Asset derivatives Other current assets $ 1.3 Liability derivatives Accrued expenses and other $ 5.4

Equity

Equity	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Equity	Equity Total equity as of June 30, 2015 increased $1,759.0 million compared to December 31, 2014 . This increase was driven by net income attributable to Biogen Inc. and an increase in additional paid in capital resulting from our share-based compensation arrangements, partially offset by other comprehensive losses and a reduction in additional paid-in-capital resulting from the repurchase and retirement of common stock as described below. Share Repurchases In May 2015, our Board of Directors authorized a program to repurchase up to $5.0 billion of our common stock (2015 Share Repurchase Program). This authorization does not have an expiration date. We expect that purchases will be executed within a period of up to five years and that repurchased shares will be retired. The 2015 Share Repurchase Program is in addition to the approximately 1.3 million shares remaining under our February 2011 Share Repurchase Program (2011 Share Repurchase Program), which has been used principally to offset common stock issuances under our share-based compensation plans. During the six months ended June 30, 2015 , we repurchased and retired approximately 0.1 million shares of common stock at a cost of $42.2 million under our 2015 Share Repurchase Program and did not repurchase any shares of common stock under our 2011 Share Repurchase Program. During the six months ended June 30, 2014 , we purchased approximately 1.2 million shares of common stock at a cost of $336.9 million under our 2011 Share Repurchase Program. Noncontrolling Interests The following table reconciles equity attributable to noncontrolling interests (NCI): For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 NCI, beginning of period $ 2.7 $ 4.4 $ 5.0 $ 0.6 Net income (loss) attributable to NCI, net of tax (2.5 ) 8.6 (4.8 ) 8.4 Fair value of net assets and liabilities acquired and assigned to NCI — — — 4.0 Distribution to NCI — (9.1 ) — (9.1 ) Translation adjustment and other 0.2 — 0.2 — NCI, end of period $ 0.4 $ 3.9 $ 0.4 $ 3.9

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table summarizes the changes in accumulated other comprehensive income (loss), net of tax by component: (In millions) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Foreign Currency Forward Contracts Unfunded Status of Postretirement Benefit Plans Translation Adjustments Total Balance, as of December 31, 2014 $ (0.4 ) $ 71.7 $ (31.6 ) $ (99.2 ) $ (59.5 ) Other comprehensive income (loss) before reclassifications 0.9 66.1 4.1 (37.8 ) 33.3 Amounts reclassified from accumulated other comprehensive income (loss) 0.2 (75.0 ) — — (74.8 ) Net current period other comprehensive income (loss) 1.1 (8.9 ) 4.1 (37.8 ) (41.5 ) Balance, as of June 30, 2015 $ 0.7 $ 62.8 $ (27.5 ) $ (137.0 ) $ (101.0 ) (In millions) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Foreign Currency Forward Contracts Unfunded Status of Postretirement Benefit Plans Translation Adjustments Total Balance, as of December 31, 2013 $ 5.6 $ (23.7 ) $ (19.6 ) $ 10.0 $ (27.7 ) Other comprehensive income (loss) before reclassifications 1.4 6.5 0.6 (11.0 ) (2.5 ) Amounts reclassified from accumulated other comprehensive income (loss) (6.6 ) 10.1 — — 3.5 Net current period other comprehensive income (loss) (5.2 ) 16.6 0.6 (11.0 ) 1.1 Balance, as of June 30, 2014 $ 0.4 $ (7.1 ) $ (19.0 ) $ (1.0 ) $ (26.7 ) The following table summarizes the amounts reclassified from accumulated other comprehensive income: (In millions) Income Statement Location Amounts Reclassified from Accumulated Other Comprehensive Income For the Three Months For the Six Months 2015 2014 2015 2014 Gains (losses) on securities available for sale Other income (expense) $ (0.2 ) $ 10.1 $ (0.3 ) $ 10.2 Income tax benefit (expense) 0.1 (3.6 ) 0.1 (3.6 ) Gains (losses) on foreign currency forward contracts Revenues 40.4 (5.3 ) 75.4 (10.0 ) Income tax benefit (expense) (0.2 ) (0.5 ) (0.4 ) (0.1 ) Total reclassifications, net of tax $ 40.1 $ 0.7 $ 74.8 $ (3.5 )

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic and diluted earnings per share are calculated as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Numerator: Net income attributable to Biogen Inc. $ 927.3 $ 714.5 $ 1,749.8 $ 1,194.5 Denominator: Weighted average number of common shares outstanding 235.3 236.7 235.1 236.7 Effect of dilutive securities: Stock options and employee stock purchase plan 0.1 0.1 0.1 0.1 Time-vested restricted stock units 0.2 0.4 0.3 0.5 Market stock units 0.1 0.2 0.2 0.3 Dilutive potential common shares 0.4 0.7 0.6 0.9 Shares used in calculating diluted earnings per share 235.7 237.4 235.7 237.6 Amounts excluded from the calculation of net income per diluted share because their effects were anti-dilutive were not significant.

Share-based Payments

Share-based Payments	6 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Payments	Share-based Payments Share-based Compensation Expense The following table summarizes share-based compensation expense included within our condensed consolidated statements of income: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Research and development $ 22.1 $ 24.5 $ 57.5 $ 53.9 Selling, general and administrative 26.2 33.6 81.8 80.8 Subtotal 48.3 58.1 139.3 134.7 Capitalized share-based compensation costs (2.2 ) (2.6 ) (5.6 ) (5.2 ) Share-based compensation expense included in total cost and expenses 46.1 55.5 133.7 129.5 Income tax effect (12.9 ) (16.5 ) (39.6 ) (38.8 ) Share-based compensation expense included in net income attributable to Biogen Inc. $ 33.2 $ 39.0 $ 94.1 $ 90.7 The following table summarizes share-based compensation expense associated with each of our share-based compensation programs: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Market stock units $ 9.1 $ 8.2 $ 26.1 23.1 Time-vested restricted stock units 31.8 29.2 63.7 58.4 Cash settled performance units 3.2 14.0 27.0 35.4 Performance units 1.2 4.0 14.4 10.3 Employee stock purchase plan 3.0 2.7 8.1 7.5 Subtotal 48.3 58.1 139.3 134.7 Capitalized share-based compensation costs (2.2 ) (2.6 ) (5.6 ) (5.2 ) Share-based compensation expense included in total cost and expenses $ 46.1 $ 55.5 $ 133.7 $ 129.5 Grants Under Share-based Compensation Plans The following table summarizes our equity grants to employees, officers and directors under our current stock plans: For the Six Months 2015 2014 Market stock units 179,000 222,000 Cash settled performance shares 115,000 180,000 Performance units 89,000 50,000 Time-vested restricted stock units 375,000 418,000 Employee Stock Purchase Plan (ESPP) In June 2015, our stockholders approved the Biogen Inc. 2015 Employee Stock Purchase Plan (ESPP). The ESPP, which became effective on July 1, 2015, replaced the Biogen Idec Inc. 1995 ESPP (1995 ESPP), which expired on June 30, 2015. The maximum aggregate number of shares of our common stock that may be purchased under the ESPP is 6,200,000 . For the six months ended June 30, 2015 , approximately 98,000 shares were issued under our 1995 ESPP compared to approximately 112,000 shares issued in the prior year comparative period.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three and six months ended June 30, 2015 , our effective tax rate was 23.9% and 24.7% , respectively, as compared to 27.0% and 26.9% , respectively, in the prior year comparative periods. A reconciliation between the U.S. federal statutory tax rate and our effective tax rate is summarized as follows: For the Three Months For the Six Months 2015 2014 2015 2014 Statutory rate 35.0 % 35.0 % 35.0 % 35.0 % State taxes 0.4 1.1 — 1.1 Taxes on foreign earnings (11.1 ) (8.7 ) (9.8 ) (8.5 ) Credits and net operating loss utilization (0.7 ) (0.7 ) (0.7 ) (0.9 ) Purchased intangible assets 1.1 1.2 1.0 1.3 Manufacturing deduction (2.1 ) (1.7 ) (1.8 ) (1.8 ) Other permanent items 0.9 0.4 0.7 0.4 Other 0.4 0.4 0.3 0.3 Effective tax rate 23.9 % 27.0 % 24.7 % 26.9 % For the three months ended June 30, 2015 , compared to the same period in 2014 , the decrease in our effective income tax rate is due to lower anticipated taxes on foreign earnings. For the six months ended June 30, 2015 , compared to the same period in 2014 , the decrease in our income tax rate was due to a benefit resulting from the remeasurement of one of our uncertain tax positions, described below, and lower anticipated taxes on foreign earnings. Accounting for Uncertainty in Income Taxes We and our subsidiaries are routinely examined by various taxing authorities. We file income tax returns in the U.S. federal jurisdiction, various U.S. states, and foreign jurisdictions. With few exceptions, including the proposed disallowance we discuss below, we are no longer subject to U.S. federal tax examination for years before 2013 or state, local, or non-U.S. income tax examinations for years before 2004. In March 2015, we received a final assessment from the Danish Tax Authority (SKAT) for fiscal 2009, regarding withholding taxes and the treatment of certain intercompany transactions involving our Danish affiliate and another of our affiliates. The audits of our tax filings for 2010 through 2013 are not completed but have been prepared in a manner consistent with prior filings, with similar transactions, which may result in an assessment for those years. The total amount assessed for 2009 is $48.3 million , including interest. For all periods potentially under dispute, we believe that positions taken in our tax filings are valid and we are contesting the assessment vigorously. Federal Uncertain Tax Positions During the six months ended June 30, 2015 , the net effect of adjustments to our uncertain tax positions was a net benefit of approximately $24.0 million primarily related to the state impact of a federal uncertain tax item. It is reasonably possible that we will adjust the value of our uncertain tax positions related to our unconsolidated joint business and certain transfer pricing issues as we receive additional information from various taxing authorities, including reaching settlements with the authorities. In addition, the Internal Revenue Service (IRS) and other national tax authorities routinely examine our intercompany transfer pricing with respect to intellectual property related transactions and it is possible that they may disagree with one or more positions we have taken with respect to such valuations. In October 2011, in conjunction with our examination, the IRS proposed a disallowance of approximately $130.0 million in deductions for tax years 2007, 2008 and 2009 related to payments for services provided by our wholly owned Danish subsidiary located in Hillerød, Denmark. We believe that these items represent valid deductible business expenses and are vigorously defending our position. We have initiated a mutual agreement procedure between the IRS and SKAT for the years 2001 through 2009, in an attempt to reach agreement on the issue. In addition, we have applied for a bilateral advanced pricing agreement for the years 2010 through 2014 to resolve similar issues for the subsequent years.

Other Consolidated Financial St

Other Consolidated Financial Statement Detail	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Consolidated Financial Statement Detail	Other Consolidated Financial Statement Detail Other Income (Expense), Net Components of other income (expense), net, are summarized as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Interest income $ 4.3 $ 2.4 $ 7.6 $ 5.1 Interest expense (5.8 ) (7.1 ) (12.5 ) (14.7 ) Gain (loss) on investments, net 0.3 13.6 (1.4 ) 16.6 Foreign exchange gains (losses), net (1.5 ) (1.4 ) (14.5 ) (4.7 ) Other, net (8.2 ) (2.6 ) (5.1 ) (3.0 ) Total other income (expense), net $ (10.9 ) $ 4.9 $ (25.9 ) $ (0.7 ) Other Current Assets Other current assets includes prepaid taxes totaling approximately $280.5 million and $57.6 million as of June 30, 2015 and December 31, 2014 , respectively. Accrued Expenses and Other Accrued expenses and other consists of the following: (In millions) As of As of Current portion of contingent consideration obligations $ 493.5 $ 265.5 Revenue-related rebates 446.5 359.2 Employee compensation and benefits 214.4 393.8 Royalties and licensing fees 161.9 172.4 Deferred revenue 62.5 120.9 Other 433.3 507.5 Total accrued expenses and other $ 1,812.1 $ 1,819.3 Other Long-Term Liabilities Other long-term liabilities consist of the following: (In millions) As of As of Contingent consideration obligations $ 302.2 $ 200.0 Employee compensation and benefits 224.5 200.7 Other 389.0 249.4 Total other long-term liabilities $ 915.7 $ 650.1 Pricing of TYSABRI in Italy - AIFA In the fourth quarter of 2011, Biogen Italia SRL (formerly Biogen Idec Italia SRL), our Italian subsidiary, received notice from the Italian National Medicines Agency (Agenzia Italiana del Farmaco or AIFA) that sales of TYSABRI after mid-February 2009 exceeded a reimbursement limit established pursuant to a Price Determination Resolution granted by AIFA in December 2006. In December 2011, we filed an appeal against AIFA in administrative court in Rome, Italy seeking a ruling that the reimbursement limit is unenforceable. That appeal is pending. In June 2014, AIFA approved a resolution, effective for a 24 month term, setting the price for TYSABRI in Italy. This resolution also eliminated the reimbursement limit from February 2013 going forward. As a result, in June 2014, we recognized $53.5 million of TYSABRI revenues related to the periods beginning February 2013 that were previously deferred. In October 2014, we proposed a settlement to resolve all of AIFA's claims relating to sales of TYSABRI in excess of the reimbursement limit for the period from mid-February 2009 through January 2013 for an aggregate lump sum repayment of EUR 35.6 million . The settlement agreement was sent to the Avvocatura Generale dello Stata (Attorney General) for its opinion. In June 2015, the Attorney General chose not to approve the settlement. AIFA and Biogen Italia SRL continue to discuss a possible resolution for this period. We have approximately EUR 75 million recorded as accrued expenses and deferred revenue included within our long-term liabilities within our condensed consolidated balance sheets for this matter. For additional information relating to our agreement with AIFA relating to sales of TYSABRI in Italy, please read Note 4, Accounts Receivable to our consolidated financial statements included within our 2014 Form 10-K.

Investments in Variable Interes

Investments in Variable Interest Entities	6 Months Ended
	Jun. 30, 2015
Investments in Variable Interest Entities [Abstract]
Investments in Variable Interest Entities	Investments in Variable Interest Entities Consolidated Variable Interest Entities Our condensed consolidated financial statements include the financial results of variable interest entities in which we are the primary beneficiary. Neurimmune SubOne AG In 2007, we entered into a collaboration agreement with Neurimmune SubOne AG (Neurimmune), a subsidiary of Neurimmune AG, for the development and commercialization of antibodies for the treatment of Alzheimer’s disease. Neurimmune conducts research to identify potential therapeutic antibodies and we are responsible for the development, manufacturing and commercialization of all products. Our anti-amyloid beta antibody, aducanumab (BIIB037), for the treatment of Alzheimer’s disease resulted from this collaboration. In December 2014, we reported positive interim data from the Phase 1b trial of aducanumab. Based upon our current development plans, we may pay Neurimmune up to $335.0 million in remaining milestone payments, of which $60.0 million is payable upon dosing of the first patient in a Phase 3 trial for aducanumab. We may also pay royalties in the low-to-mid-teens on sales of any resulting commercial products. Amounts that are incurred by Neurimmune for research and development expenses in support of the collaboration that we reimburse are reflected in research and development expense in our condensed consolidated statements of income. Future milestone payments, if any, will be reflected within our condensed consolidated statements of income as a charge to noncontrolling interest, net of tax, when such milestones are achieved. For the three and six months ended June 30, 2015 , the collaboration incurred expenses totaling $35.0 million and $47.8 million , respectively, which is included in total costs and expenses within our condensed consolidated statements of income, as compared to $10.6 million and $21.7 million , respectively, in the prior year comparative periods. The assets and liabilities of Neurimmune are not significant to our financial position or results of operations as it is a research and development organization. We have provided no financing to Neurimmune other than contractually required amounts. Unconsolidated Variable Interest Entities We have relationships with other variable interest entities that we do not consolidate as we lack the power to direct the activities that significantly impact the economic success of these entities. These relationships include investments in certain biotechnology companies and research collaboration agreements. As of June 30, 2015 and December 31, 2014 , the total carrying value of our investments in biotechnology companies totaled $8.5 million and $7.9 million , respectively. Our maximum exposure to losses related to these variable interest entities is limited to the carrying value of our investments. We have entered into research collaboration agreements with certain variable interest entities where we are required to fund certain development activities. These development activities are included in research and development expense within our condensed consolidated statements of income, as they are incurred. We have provided no financing to these variable interest entities other than previously contractually required amounts. For additional information related to our investments in variable interest entities, please read Note 19, Investments in Variable Interest Entities to our consolidated financial statements included within our 2014 Form 10-K.

Collaborative and Other Relatio

Collaborative and Other Relationships	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative and Other Relationships	Collaborative and Other Relationships Samsung Bioepis Joint Venture Agreement In February 2012, we entered into a joint venture agreement with Samsung BioLogics Co. Ltd. (Samsung Biologics), establishing an entity, Samsung Bioepis, to develop, manufacture and market biosimilar pharmaceuticals. Samsung Biologics contributed 280.5 billion South Korean won (approximately $250.0 million ) for an 85% stake in Samsung Bioepis and we contributed approximately 49.5 billion South Korean won (approximately $45.0 million ) for the remaining 15% ownership interest. Under the joint venture agreement, we have no obligation to provide any additional funding and our ownership interest may be diluted due to financings in which we do not participate. As of June 30, 2015 , our ownership interest is approximately 10% , which reflects our additional contribution of 6.3 billion South Korean won (approximately $5.7 million ) in the first quarter of 2015 and the effect of additional equity financings in which we did not participate. We maintain an option to purchase additional stock in Samsung Bioepis that would allow us to increase our ownership percentage up to 49.9% . The exercise of this option is within our control and is based on paying for 49.9% of the total investment made by Samsung Biologics into Samsung Bioepis in excess of what we have already contributed under the agreement plus interest. As of June 30, 2015 and December 31, 2014 , the carrying value of our investment in Samsung Bioepis totaled 7.5 billion and 9.1 billion South Korean won (approximately $6.8 million and $8.6 million ), respectively, which is classified as a component of investments and other assets within our condensed consolidated balance sheets. Based on our level of influence over Samsung Bioepis, we account for this investment under the equity method of accounting and we recognize our share of the results of operations related to our investment in Samsung Bioepis one quarter in arrears when the results of the entity become available, which is reflected as equity in loss of investee, net of tax within our condensed consolidated statements of income. During the three and six months ended June 30, 2015 , we recognized a loss on our investment of $4.9 million and $5.7 million , respectively, as compared to $1.9 million and $9.5 million , respectively, in the prior year comparative periods. Commercial Agreement On December 17, 2013, pursuant to our rights under the joint venture agreement with Samsung Biologics, we entered into an agreement with Samsung Bioepis to commercialize anti-tumor necrosis factor (TNF) biosimilar product candidates in Europe and, in the case of one anti-TNF biosimilar candidate, Japan. Under the terms of this agreement, we have paid $46.0 million , which has been recorded as a research and development expense within our condensed consolidated statements of income as the programs they relate to have not achieved regulatory approval. Samsung Bioepis is eligible to receive an additional $75.0 million in additional milestones related to clinical development and regulatory approval of the product candidates. Upon commercialization, there will be a 50% profit share with Samsung Bioepis. Other Services Simultaneous with the formation of Samsung Bioepis, we also entered into a license agreement, a technical development services agreement and a manufacturing agreement with Samsung Bioepis. For the three and six months ended June 30, 2015 , we recognized $17.2 million and $36.1 million , respectively, in other revenues in relation to these services, as compared to $12.3 million and $36.5 million , respectively, in the prior year comparative periods. For additional information related to our other significant collaboration arrangements, please read Note 20, Collaborative and Other Relationships to our consolidated financial statements included within our 2014 Form 10-K.

Litigation

Litigation	6 Months Ended
	Jun. 30, 2015
Loss Contingency, Information about Litigation Matters [Abstract]
Litigation	Litigation ’755 Patent Litigation On May 28, 2010, Biogen MA Inc. (formerly Biogen Idec MA Inc.) filed a complaint in the U.S. District Court for the District of New Jersey alleging infringement by Bayer Healthcare Pharmaceuticals Inc. (Bayer) (manufacturer, marketer and seller of BETASERON and manufacturer of EXTAVIA), EMD Serono, Inc. (manufacturer, marketer and seller of REBIF), Pfizer Inc. (co-marketer of REBIF), and Novartis Pharmaceuticals Corp. (marketer and seller of EXTAVIA) of our U.S. Patent No. 7,588,755 (’755 Patent), which claims the use of interferon beta for immunomodulation or treating a viral condition, viral disease, cancers or tumors. The complaint seeks monetary damages, including lost profits and royalties. Bayer had previously filed a complaint against us in the same court, on May 27, 2010, seeking a declaratory judgment that it does not infringe the ’755 Patent and that the patent is invalid, and seeking monetary relief in the form of attorneys' fees, costs and expenses. The court has consolidated the two lawsuits, and we refer to the two actions as the “Consolidated ’755 Patent Actions.” Bayer, Pfizer, Novartis and EMD Serono have all filed counterclaims in the Consolidated ’755 Patent Actions seeking declaratory judgments of patent invalidity and non-infringement, and seeking monetary relief in the form of costs and attorneys' fees, and EMD Serono and Bayer have each filed a counterclaim seeking a declaratory judgment that the ’755 Patent is unenforceable based on alleged inequitable conduct. Bayer has also amended its complaint to seek such a declaration. No trial date has been set. Italian National Medicines Agency In the fourth quarter of 2011, Biogen Italia SRL received notice from the Italian National Medicines Agency (Agenzia Italiana del Farmaco or AIFA) that sales of TYSABRI after mid-February 2009 exceeded a reimbursement limit established pursuant to a Price Determination Resolution (Price Resolution) granted by AIFA in December 2006. On December 23, 2011, we filed an appeal in the Regional Administrative Tribunal of Lazio (Il Tribunale Amministrativo Regionale per il Lazio) in Rome, Italy seeking a ruling that the reimbursement limit in the Price Resolution should apply as written to only “the first 24 months” of TYSABRI sales, which ended in mid-February 2009. The appeal is still pending. In June 2014, AIFA approved a resolution affirming that there is no reimbursement limit from and after February 2013. AIFA and Biogen Italia SRL are discussing a possible resolution for the period from mid-February 2009 through January 2013. Government Matters We have learned that state and federal governmental authorities are investigating our sales and promotional practices and have received related subpoenas. We have also received a subpoena from the federal government for documents relating to our relationship with certain pharmacy benefit managers. We are cooperating with the government in these matters. Qui Tam Litigation On July 6, 2015, four qui tam actions filed against us by relators suing on behalf of the United States and certain states were unsealed by the U.S. District Court for the District of Massachusetts. The actions, which have been administratively consolidated, allege sales and promotional activities in violation of the federal False Claims Act and state law counterparts, and seek single and treble damages, civil penalties, interest, attorneys’ fees and costs. The United States has declined to intervene in two of the actions and has not made an intervention decision in the other two actions. We have not been served with any of the complaints. We have not formed an opinion that an unfavorable outcome in any of the actions is either “probable” or “remote” and are unable to estimate the magnitude or range of any potential loss. Forward Pharma Litigation On November 18, 2014 Forward Pharma A/S (Forward Pharma) filed suit against us in the Regional Court of Dusseldorf, Germany alleging that TECFIDERA infringes German Utility Model DE 20 2005 022 112 U1, which was issued in April 2014 and expires in October 2015. Forward Pharma subsequently extended its allegations to assert that TECFIDERA infringes Forward Pharma's European Patent No. 2,801,355, which was issued in May 2015 and expires in October 2025. Forward Pharma seeks declarations of infringement and damages. A hearing has been scheduled for early 2016. We have not formed an opinion that an unfavorable outcome is either “probable” or “remote” and are unable to estimate the magnitude or range of any potential loss. Product Liability and Other Legal Proceedings We are also involved in product liability claims and other legal proceedings generally incidental to our normal business activities. While the outcome of any of these proceedings cannot be accurately predicted, we do not believe the ultimate resolution of any of these existing matters would have a material adverse effect on our business or financial condition.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure	Commitments and Contingencies Fumapharm AG In 2006, we acquired Fumapharm AG. As part of this acquisition we acquired FUMADERM and TECFIDERA (together, Fumapharm Products). We paid $220.0 million upon the closing of the transaction and agreed to pay an additional $15.0 million if a Fumapharm Product was approved for MS in the U.S. or E.U. In the second quarter of 2013, we paid this $15.0 million contingent payment as TECFIDERA was approved in the U.S. for MS by the U.S. Food and Drug Administration (FDA). We are also required to make additional contingent payments to former shareholders of Fumapharm AG or holders of their rights based on the attainment of certain cumulative sales levels of Fumapharm Products and the level of total net sales of Fumapharm Products in the prior twelve month period, as defined in the acquisition agreement. During the six months ended June 30, 2015 , we paid a $250.0 million contingent payment as we reached the $4.0 billion cumulative sales level related to the Fumapharm Products in the fourth quarter of 2014 and accrued $300.0 million upon reaching $5.0 billion in total cumulative sales of Fumapharm Products in the second quarter of 2015. We will owe an additional $300.0 million contingent payment for every additional $1.0 billion in cumulative sales level of Fumapharm Products reached if the prior 12 months sales of the Fumapharm Products exceed $3.0 billion , until such time as the cumulative sales level reaches $20.0 billion , at which time no further contingent payments shall be due. These payments will be accounted for as an increase to goodwill as incurred, in accordance with the accounting standard applicable to business combinations when we acquired Fumapharm. Any portion of the payment which is tax deductible will be recorded as a reduction to goodwill. Payments are due within 60 days following the end of the quarter in which the applicable cumulative sales level has been reached. Solothurn, Switzerland Facility On June 30, 2015, we signed an agreement to purchase land in Solothurn, Switzerland for 65.1 million Swiss Francs. The contract also includes certain environmental remediation costs. Our obligation to purchase the land under the contract is subject to customary closing conditions as well as a condition that no material adverse changes in our business such as a decision to discontinue our aducanumab program have occurred during the period.

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events	6 Months Ended
	Jun. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Applied Genetic Technologies Corporation On July 2, 2015, we announced a collaboration and license agreement to develop gene-based therapies for multiple ophthalmic diseases with Applied Genetic Technologies Corporation (AGTC). The collaboration will focus on the development of a portfolio of AGTC’s therapeutic programs, including both a clinical stage candidate for X-linked Retinoschisis (XLRS) and a pre-clinical candidate for the treatment of X-Linked Retinitis Pigmentosa (XLRP). The agreement also includes options for early stage discovery programs in two ophthalmic diseases and one non-ophthalmic condition, as well as an equity investment in AGTC by Biogen and a license agreement for manufacturing rights. Upon closing, we will make an upfront payment in the amount of $124.0 million to AGTC, which includes a $30.0 million equity investment in AGTC, prepaid research and development expenditures of $58.4 million and total licensing and other fees of $35.6 million . We will be granted a license to the XLRS and XLRP programs and the option to license discovery programs for three additional indications at the time of clinical candidate selection. Under the collaboration, AGTC is eligible to receive upfront and milestone payments aggregating in excess of $1.0 billion . This includes up to $472.5 million collectively for the two lead programs, which also will carry royalties in the high single digit to mid-teen percentages of annual net sales. In addition, we will make payments up to $592.5 million across the discovery programs, along with royalties in the mid-single digits to low-teen percentages of annual net sales. We will be granted worldwide commercialization rights for the XLRS and XLRP programs. AGTC has an option to share development costs and profits after the initial clinical trial data are available, and an option to co-promote the second of these products to be approved in the U.S. AGTC will lead the clinical development programs of XLRS through product approval and of XLRP through the completion of first-in-human trials. We will support the clinical development costs, subject to certain conditions, following the first-in-human study for XLRS and IND-enabling studies for XLRP. Under the manufacturing license, we will receive an exclusive license to use AGTC’s proprietary technology platform to make AAV vectors for up to six genes, three of which are in AGTC’s discretion, in exchange for payment of milestones and royalties. The transaction is subject to customary closing conditions, including the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 in the U.S., and is expected to close in the third quarter of 2015. Research Triangle Park Facility Purchase On July 15, 2015, we entered into an arrangement with Eisai, Inc. (Eisai) to purchase their manufacturing facility in Research Triangle Park, North Carolina, including a drug product facility and supporting infrastructure. Currently, we are leasing a portion of this facility in order to manufacture our and Eisai's oral solid dose products under a 10 year lease. We have committed to buy that portion of the facility upon Eisai’s completion of certain transition activities. The transaction is subject to customary closing conditions, including the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 in the U.S., and is expected to close in the third quarter of 2015. Swedish Orphan Biovitrum AB On July 16, 2015, Swedish Orphan Biovitrum AB (Sobi) exercised its option to assume development and commercialization of ALPROLIX in Europe, Russia, Turkey and certain markets in the Middle East and paid us $10.0 million , which will be held in escrow pending E.U. regulatory approval. We collaborate with Sobi to jointly develop and commercialize Factor VIII and Factor IX hemophilia products, including ELOCTATE and ALPROLIX. For more information about our agreement with Sobi, please read Note 20, Collaborative and Other Relationships to our consolidated financial statements included within our 2014 Form 10-K.

Summary of Significant Accoun27

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Overview	Biogen is a global biopharmaceutical company focused on discovering, developing, manufacturing and delivering therapies for neurological, autoimmune and hematologic disorders. Our principal marketed products include AVONEX, PLEGRIDY, TECFIDERA, TYSABRI, and FAMPYRA for multiple sclerosis (MS), ALPROLIX for hemophilia B and ELOCTATE for hemophilia A. We also collaborate with Genentech, Inc., a wholly-owned member of the Roche Group, on the development and commercialization of RITUXAN for the treatment of non-Hodgkin's lymphoma, chronic lymphocytic leukemia and other conditions and share profits and losses for GAZYVA, which is approved for the treatment of chronic lymphocytic leukemia.
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 presentation 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, 2014 ( 2014 Form 10-K). Our accounting policies are described in the “ Notes to Consolidated Financial Statements ” in our 2014 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 our audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2015 , are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.
Consolidation	Our condensed consolidated financial statements reflect our financial statements, those of our wholly-owned subsidiaries and those of certain variable interest entities where we are the primary beneficiary. For consolidated entities where 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. Intercompany balances and transactions are eliminated in consolidation. In determining whether we are the primary beneficiary of an entity and therefore required to consolidate, 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 other arrangements. We continuously assess whether we are the primary beneficiary of a variable interest entity as changes to existing relationships or future transactions may result in us consolidating or deconsolidating one or more of our collaborators or partners. We operate as one operating segment, which is focused on discovering, developing, manufacturing and delivering therapies for neurological, autoimmune and hematologic disorders.
Use of estimates	The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that may affect the reported amounts of assets, liabilities, equity, revenues and expenses, and related disclosure of contingent assets and liabilities. On an on-going basis, we evaluate our estimates and judgments and methodologies. 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.
Accounts receivable	Our accounts receivable primarily arise from product sales in the U.S. and Europe and mainly represent amounts due from our wholesale distributors, public hospitals and other government entities. Concentrations of credit risk with respect to our accounts receivable, which are typically unsecured, are limited due to the wide variety of customers and markets using our products, as well as their dispersion across many different geographic areas. The majority of our accounts receivable require payment within 30 to 90 days . We monitor the financial performance and credit worthiness of our customers so that we can properly assess and respond to changes in their credit profile. We provide reserves against trade receivables for estimated losses that may result from a customer’s inability to pay. Amounts determined to be uncollectible are charged or written-off against the reserve. To date, our historical reserves and write-offs of accounts receivable have not been significant. In countries where we have experienced a pattern of payments extending beyond our contractual payment term and we expect to collect receivables greater than one year after the time of sale, we have discounted our receivables and reduced related revenues over the period of time that we estimate those amounts will be paid using the country’s market-based borrowing rate for such period. The related receivables are classified at the time of sale as non-current assets. We accrete interest income on these receivables, which is recognized as a component of other income (expense), net within our condensed consolidated statement of income.
Property, plant and equipment	Property, plant and equipment are recorded at cost, net of accumulated depreciation. Accumulated depreciation on property, plant and equipment was $1,274.2 million and $1,186.4 million as of June 30, 2015 and December 31, 2014 , respectively.
New accounting pronouncements	From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (FASB) or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed, we do not believe that the impact of recently issued standards that are not yet effective will have a material impact on our financial position or results of operations upon adoption. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. In July 2015, the FASB decided to delay the effective date of the new revenue standard by one year. The new standard will be effective for us on January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. We are currently evaluating the method of adoption and the potential impact that Topic 606 may have on our financial position and results of operations. In June 2014, the FASB issued ASU No. 2014-11, Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosure. The new standard expanded secured borrowing accounting to include repurchase-to-maturity transactions and repurchase financings and set forth new disclosure requirements for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. We adopted this standard on April 1, 2015 and expanded our disclosures presented within Note 7, Financial Instruments to these condensed consolidated financial statements. The adoption of this standard did not have an impact on our financial position or results of operations. In April 2015, the FASB issued ASU No. 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The new standard requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new standard will be effective for us on January 1, 2016. The adoption of this standard is not expected to have an impact on our financial position or results of operations. In April 2015, the FASB issued ASU No. 2015-05, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. Under this standard, if a cloud computing arrangement includes a software license, the software license element of the arrangement should be accounted for consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the arrangement should be accounted for as a service contract. The new standard will be effective for us on January 1, 2016. The adoption of this standard is not expected to have an impact on our financial position or results of operations. In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). The new standard removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. The new standard will be effective for us on January 1, 2016. Early application is permitted. We maintain investments in certain venture capital funds which primarily invest in small, privately-owned, venture-backed biotechnology companies. The value of our investments in these venture capital funds is estimated using the net asset value of the fund and has been included in the fair value hierarchy disclosure as a Level 3 measurement. These venture capital investments are not material to our financial position or results of operations. We have elected to apply this standard as of June 30, 2015 and our investments in venture capital funds will no longer be included in our disclosures reflected within Note 6, Fair Value Measurements to these condensed consolidated financial statements.

Acquisitions Acquisitions (Tabl

Acquisitions Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Purchase price schedule	he purchase price, as adjusted, consisted of the following: (In millions) Cash portion of consideration $ 200.1 Contingent consideration 274.5 Total purchase price $ 474.6
Estimated fair values of the separately identifiable assets acquired and liabilities assumed	he following table summarizes the estimated fair values of the separately identifiable assets acquired and liabilities assumed as of February 12, 2015, as adjusted: (In millions) In-process research and development $ 424.6 Other intangible assets 7.6 Goodwill 128.3 Deferred tax liability (84.9 ) Other, net (1.0 ) Total purchase price $ 474.6

Reserves for Discounts and Al29

Reserves for Discounts and Allowances (Tables)	6 Months Ended
	Jun. 30, 2015
Sales Discounts, Returns and Allowances, Goods [Abstract]
Analysis of the changes in reserves	An analysis of the change in reserves for discounts and allowances is summarized as follows: (In millions) Discounts Contractual Adjustments Returns Total Balance, as of December 31, 2014 $ 47.6 $ 387.1 $ 49.1 $ 483.8 Current provisions relating to sales in current year 209.2 854.4 19.1 1,082.7 Adjustments relating to prior years 0.4 (19.8 ) (8.1 ) (27.5 ) Payments/credits relating to sales in current year (158.0 ) (483.9 ) (0.9 ) (642.8 ) Payments/credits relating to sales in prior years (43.3 ) (254.7 ) (7.8 ) (305.8 ) Balance, as of June 30, 2015 $ 55.9 $ 483.1 $ 51.4 $ 590.4
Total reserves included in condensed consolidated balance sheets	The total reserves above, included in our condensed consolidated balance sheets, are summarized as follows: (In millions) As of As of Reduction of accounts receivable $ 143.9 $ 124.6 Component of accrued expenses and other 446.5 359.2 Total reserves $ 590.4 $ 483.8

Inventory (Tables)

Inventory (Tables)	6 Months Ended
	Jun. 30, 2015
Inventory Disclosure [Abstract]
Components of inventory	The components of inventory are summarized as follows: (In millions) As of As of Raw materials $ 173.2 $ 128.3 Work in process 516.7 511.5 Finished goods 175.8 164.2 Total inventory $ 865.7 $ 804.0

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	6 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets	Intangible assets, net of accumulated amortization, impairment charges and adjustments, are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Estimated Life Cost Accumulated Amortization Net Cost Accumulated Amortization Net Out-licensed patents 13-23 years $ 543.3 $ (493.9 ) $ 49.4 $ 543.3 $ (481.7 ) $ 61.6 Developed technology 15-23 years 3,005.3 (2,492.1 ) 513.2 3,005.3 (2,396.8 ) 608.5 In-process research and development Indefinite until commercialization 752.0 — 752.0 314.1 — 314.1 Trademarks and tradenames Indefinite 64.0 — 64.0 64.0 — 64.0 Acquired and in-licensed rights and patents 3-17 years 3,296.7 (380.5 ) 2,916.2 3,280.4 (300.1 ) 2,980.3 Total intangible assets $ 7,661.3 $ (3,366.5 ) $ 4,294.8 $ 7,207.1 $ (3,178.6 ) $ 4,028.5
Estimated future amortization for acquired intangible assets	Based upon this recent analysis, the estimated future amortization for acquired intangible assets is expected to be as follows: (In millions) As of 2015 (remaining six months) $ 185.5 2016 312.5 2017 285.8 2018 281.6 2019 270.6 2020 263.8 Total $ 1,599.8
Summary of roll forward of the changes in goodwill	The following table provides a roll forward of the changes in our goodwill balance: (In millions) Balance, as of December 31, 2014 $ 1,760.2 Increase to goodwill 390.0 Other 4.1 Balance, as of June 30, 2015 $ 2,154.3

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Summary of assets and liabilities recorded at fair value	The tables below present information about our assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques we utilized to determine such fair value: As of June 30, 2015 (In millions) Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 974.0 $ — $ 974.0 $ — Marketable debt securities: Corporate debt securities 1,198.1 — 1,198.1 — Government securities 1,700.3 — 1,700.3 — Mortgage and other asset backed securities 290.0 — 290.0 — Marketable equity securities 6.8 6.8 — — Derivative contracts 100.5 — 100.5 — Plan assets for deferred compensation 40.7 — 40.7 — Total $ 4,310.4 $ 6.8 $ 4,303.6 $ — Liabilities: Derivative contracts $ 27.7 $ — $ 27.7 $ — Contingent consideration obligations 495.6 — — 495.6 Total $ 523.3 $ — $ 27.7 $ 495.6 As of December 31, 2014 (In millions) Total Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 716.3 $ — $ 716.3 $ — Marketable debt securities: Corporate debt securities 1,063.0 — 1,063.0 — Government securities 849.8 — 849.8 — Mortgage and other asset backed securities 198.3 — 198.3 — Marketable equity securities 6.9 6.9 — — Derivative contracts 72.7 — 72.7 — Plan assets for deferred compensation 36.9 — 36.9 — Total $ 2,943.9 $ 6.9 $ 2,937.0 $ — Liabilities: Derivative contracts $ 5.4 $ — $ 5.4 $ — Contingent consideration obligations 215.5 — — 215.5 Total $ 220.9 $ — $ 5.4 $ 215.5
Summary of fair and carrying value of debt instruments	The fair and carrying values of our debt instruments, which are Level 2 liabilities, are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Fair Value Carrying Value Fair Value Carrying Value Notes payable to Fumedica $ 10.0 $ 9.4 $ 12.6 $ 11.7 6.875% Senior Notes due March 1, 2018 621.5 570.1 634.6 573.5 Total $ 631.5 $ 579.5 $ 647.2 $ 585.2
Fair value of contingent consideration obligations	The following table provides a roll forward of the fair values of our contingent consideration obligations which includes Level 3 measurements: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Fair value, beginning of period $ 461.8 $ 275.1 $ 215.5 $ 280.9 Additions 36.0 — 274.5 — Changes in fair value (2.2 ) 4.0 5.6 3.2 Payments — — — (5.0 ) Fair value, end of period $ 495.6 $ 279.1 $ 495.6 $ 279.1

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Marketable debt and equity securities	The following tables summarize our marketable debt and equity securities: As of June 30, 2015 (In millions) Fair Value Gross Unrealized Gains Gross Unrealized Losses Amortized Cost Available-for-sale: Corporate debt securities Current $ 375.9 $ 0.1 $ (0.1 ) $ 375.9 Non-current 822.2 0.4 (1.2 ) 823.0 Government securities Current 710.5 0.1 (0.1 ) 710.5 Non-current 989.8 0.9 (0.1 ) 989.0 Mortgage and other asset backed securities Current 0.2 — — 0.2 Non-current 289.8 0.2 (0.3 ) 289.9 Total marketable debt securities $ 3,188.4 $ 1.7 $ (1.8 ) $ 3,188.5 Marketable equity securities, non-current $ 6.8 $ 1.1 $ — $ 5.7 As of December 31, 2014 (In millions) Fair Value Gross Unrealized Gains Gross Unrealized Losses Amortized Cost Available-for-sale: Corporate debt securities Current $ 370.4 $ — $ (0.2 ) $ 370.6 Non-current 692.6 0.2 (1.5 ) 693.9 Government securities Current 269.9 — (0.1 ) 270.0 Non-current 579.9 0.3 (0.4 ) 580.0 Mortgage and other asset backed securities Current 0.2 — — 0.2 Non-current 198.1 0.2 (0.2 ) 198.1 Total marketable debt securities $ 2,111.1 $ 0.7 $ (2.4 ) $ 2,112.8 Marketable equity securities, non-current $ 6.9 $ 1.2 $ (0.2 ) $ 5.9
Summary of financial assets with maturities of less than 90 days included within cash and cash equivalents	The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included within cash and cash equivalents on the accompanying condensed consolidated balance sheet: (In millions) As of As of Commercial paper $ 38.8 $ 54.2 Overnight reverse repurchase agreements 185.0 305.0 Money market funds 740.2 321.2 Short-term debt securities 10.0 35.9 Total $ 974.0 $ 716.3
Summary of contractual maturities: available-for-sale securities	The estimated fair value and amortized cost of our marketable debt securities available-for-sale by contractual maturity are summarized as follows: As of June 30, 2015 As of December 31, 2014 (In millions) Estimated Fair Value Amortized Cost Estimated Fair Value Amortized Cost Due in one year or less $ 1,086.6 $ 1,086.6 $ 640.5 $ 640.8 Due after one year through five years 1,954.4 1,954.5 1,343.7 1,345.2 Due after five years 147.4 147.4 126.9 126.8 Total available-for-sale securities $ 3,188.4 $ 3,188.5 $ 2,111.1 $ 2,112.8
Proceeds from marketable debt securities	The proceeds from maturities and sales of marketable debt securities and resulting realized gains and losses are summarized as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Proceeds from maturities and sales $ 601.9 $ 560.1 $ 975.5 $ 1,317.5 Realized gains $ 0.3 $ 0.2 $ 0.5 $ 0.4 Realized losses $ (0.5 ) $ (0.1 ) $ (0.8 ) $ (0.2 )

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Foreign currency forward contracts that were entered into to hedge forecasted revenue	The notional value of foreign currency forward contracts that were entered into to hedge forecasted revenues is summarized as follows: Notional Amount Foreign Currency: (In millions) As of As of Euro $ 1,437.2 $ 1,174.6 Canadian dollar 32.1 56.7 British pound sterling 21.9 34.5 Japanese yen 15.5 16.6 Australian dollar 10.3 19.9 Total foreign currency forward contracts $ 1,517.0 $ 1,302.3
Summary of the effect of derivatives designated as hedging instruments on the condensed consolidated statements of income	The following table summarizes the effect of derivatives designated as hedging instruments on our condensed consolidated statements of income: For the Three Months Ended June 30, Net Gains/(Losses) Reclassified from AOCI into Operating Income (Effective Portion) Net Gains/(Losses) Recognized into Net Income (Ineffective Portion) Location 2015 2014 Location 2015 2014 Revenue $ 40.4 $ (5.2 ) Other income (expense) $ 1.2 $ (1.0 ) For the Six Months Ended June 30, Net Gains/(Losses) Reclassified from AOCI into Operating Income (Effective Portion) Net Gains/(Losses) Recognized into Net Income (Ineffective Portion) Location 2015 2014 Location 2015 2014 Revenue $ 75.4 $ (10.0 ) Other income (expense) $ 3.4 $ (1.2 )
Summary of fair value and presentation of derivatives	The following table summarizes the fair value and presentation in our condensed consolidated balance sheets of our outstanding derivatives including those designated as hedging instruments: (In millions) Balance Sheet Location Fair Value As of June 30, 2015 Hedging Instruments: Asset derivatives Other current assets $ 92.8 Liability derivatives Accrued expenses and other $ 9.8 Other long-term liabilities $ 17.2 Other Derivatives: Asset derivatives Other current assets $ 7.7 Liability derivatives Accrued expenses and other $ 0.7 (In millions) Balance Sheet Location Fair Value As of December 31, 2014 Hedging Instruments: Asset derivatives Other current assets $ 69.5 Investments and other assets $ 1.9 Other Derivatives: Asset derivatives Other current assets $ 1.3 Liability derivatives Accrued expenses and other $ 5.4

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Reconciliation of equity attributable to noncontrolling interests	The following table reconciles equity attributable to noncontrolling interests (NCI): For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 NCI, beginning of period $ 2.7 $ 4.4 $ 5.0 $ 0.6 Net income (loss) attributable to NCI, net of tax (2.5 ) 8.6 (4.8 ) 8.4 Fair value of net assets and liabilities acquired and assigned to NCI — — — 4.0 Distribution to NCI — (9.1 ) — (9.1 ) Translation adjustment and other 0.2 — 0.2 — NCI, end of period $ 0.4 $ 3.9 $ 0.4 $ 3.9

Accumulated Other Comprehensi36

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of accumulated other comprehensive income (loss)	The following table summarizes the changes in accumulated other comprehensive income (loss), net of tax by component: (In millions) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Foreign Currency Forward Contracts Unfunded Status of Postretirement Benefit Plans Translation Adjustments Total Balance, as of December 31, 2014 $ (0.4 ) $ 71.7 $ (31.6 ) $ (99.2 ) $ (59.5 ) Other comprehensive income (loss) before reclassifications 0.9 66.1 4.1 (37.8 ) 33.3 Amounts reclassified from accumulated other comprehensive income (loss) 0.2 (75.0 ) — — (74.8 ) Net current period other comprehensive income (loss) 1.1 (8.9 ) 4.1 (37.8 ) (41.5 ) Balance, as of June 30, 2015 $ 0.7 $ 62.8 $ (27.5 ) $ (137.0 ) $ (101.0 ) (In millions) Unrealized Gains (Losses) on Securities Available for Sale Unrealized Gains (Losses) on Foreign Currency Forward Contracts Unfunded Status of Postretirement Benefit Plans Translation Adjustments Total Balance, as of December 31, 2013 $ 5.6 $ (23.7 ) $ (19.6 ) $ 10.0 $ (27.7 ) Other comprehensive income (loss) before reclassifications 1.4 6.5 0.6 (11.0 ) (2.5 ) Amounts reclassified from accumulated other comprehensive income (loss) (6.6 ) 10.1 — — 3.5 Net current period other comprehensive income (loss) (5.2 ) 16.6 0.6 (11.0 ) 1.1 Balance, as of June 30, 2014 $ 0.4 $ (7.1 ) $ (19.0 ) $ (1.0 ) $ (26.7 )
Reclassification out of accumulated other comprehensive income	The following table summarizes the amounts reclassified from accumulated other comprehensive income: (In millions) Income Statement Location Amounts Reclassified from Accumulated Other Comprehensive Income For the Three Months For the Six Months 2015 2014 2015 2014 Gains (losses) on securities available for sale Other income (expense) $ (0.2 ) $ 10.1 $ (0.3 ) $ 10.2 Income tax benefit (expense) 0.1 (3.6 ) 0.1 (3.6 ) Gains (losses) on foreign currency forward contracts Revenues 40.4 (5.3 ) 75.4 (10.0 ) Income tax benefit (expense) (0.2 ) (0.5 ) (0.4 ) (0.1 ) Total reclassifications, net of tax $ 40.1 $ 0.7 $ 74.8 $ (3.5 )

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Basic and diluted earnings per share	Basic and diluted earnings per share are calculated as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Numerator: Net income attributable to Biogen Inc. $ 927.3 $ 714.5 $ 1,749.8 $ 1,194.5 Denominator: Weighted average number of common shares outstanding 235.3 236.7 235.1 236.7 Effect of dilutive securities: Stock options and employee stock purchase plan 0.1 0.1 0.1 0.1 Time-vested restricted stock units 0.2 0.4 0.3 0.5 Market stock units 0.1 0.2 0.2 0.3 Dilutive potential common shares 0.4 0.7 0.6 0.9 Shares used in calculating diluted earnings per share 235.7 237.4 235.7 237.6

Share-Based Payments (Tables)

Share-Based Payments (Tables)	6 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation expense included in condensed consolidated statements of income	The following table summarizes share-based compensation expense included within our condensed consolidated statements of income: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Research and development $ 22.1 $ 24.5 $ 57.5 $ 53.9 Selling, general and administrative 26.2 33.6 81.8 80.8 Subtotal 48.3 58.1 139.3 134.7 Capitalized share-based compensation costs (2.2 ) (2.6 ) (5.6 ) (5.2 ) Share-based compensation expense included in total cost and expenses 46.1 55.5 133.7 129.5 Income tax effect (12.9 ) (16.5 ) (39.6 ) (38.8 ) Share-based compensation expense included in net income attributable to Biogen Inc. $ 33.2 $ 39.0 $ 94.1 $ 90.7
Summary of share-based compensation expense associated with each of our share-based compensating programs	The following table summarizes share-based compensation expense associated with each of our share-based compensation programs: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Market stock units $ 9.1 $ 8.2 $ 26.1 23.1 Time-vested restricted stock units 31.8 29.2 63.7 58.4 Cash settled performance units 3.2 14.0 27.0 35.4 Performance units 1.2 4.0 14.4 10.3 Employee stock purchase plan 3.0 2.7 8.1 7.5 Subtotal 48.3 58.1 139.3 134.7 Capitalized share-based compensation costs (2.2 ) (2.6 ) (5.6 ) (5.2 ) Share-based compensation expense included in total cost and expenses $ 46.1 $ 55.5 $ 133.7 $ 129.5
Summary of equity grants to employees, officers and directors under our current stock plans	The following table summarizes our equity grants to employees, officers and directors under our current stock plans: For the Six Months 2015 2014 Market stock units 179,000 222,000 Cash settled performance shares 115,000 180,000 Performance units 89,000 50,000 Time-vested restricted stock units 375,000 418,000

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Reconciliation between the U.S. federal statutory tax rate and effective tax rate	A reconciliation between the U.S. federal statutory tax rate and our effective tax rate is summarized as follows: For the Three Months For the Six Months 2015 2014 2015 2014 Statutory rate 35.0 % 35.0 % 35.0 % 35.0 % State taxes 0.4 1.1 — 1.1 Taxes on foreign earnings (11.1 ) (8.7 ) (9.8 ) (8.5 ) Credits and net operating loss utilization (0.7 ) (0.7 ) (0.7 ) (0.9 ) Purchased intangible assets 1.1 1.2 1.0 1.3 Manufacturing deduction (2.1 ) (1.7 ) (1.8 ) (1.8 ) Other permanent items 0.9 0.4 0.7 0.4 Other 0.4 0.4 0.3 0.3 Effective tax rate 23.9 % 27.0 % 24.7 % 26.9 %

Other Consolidated Financial 40

Other Consolidated Financial Statement Detail (Tables)	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other income (expense), net	Components of other income (expense), net, are summarized as follows: For the Three Months For the Six Months (In millions) 2015 2014 2015 2014 Interest income $ 4.3 $ 2.4 $ 7.6 $ 5.1 Interest expense (5.8 ) (7.1 ) (12.5 ) (14.7 ) Gain (loss) on investments, net 0.3 13.6 (1.4 ) 16.6 Foreign exchange gains (losses), net (1.5 ) (1.4 ) (14.5 ) (4.7 ) Other, net (8.2 ) (2.6 ) (5.1 ) (3.0 ) Total other income (expense), net $ (10.9 ) $ 4.9 $ (25.9 ) $ (0.7 )
Accrued expenses and other	Accrued expenses and other consists of the following: (In millions) As of As of Current portion of contingent consideration obligations $ 493.5 $ 265.5 Revenue-related rebates 446.5 359.2 Employee compensation and benefits 214.4 393.8 Royalties and licensing fees 161.9 172.4 Deferred revenue 62.5 120.9 Other 433.3 507.5 Total accrued expenses and other $ 1,812.1 $ 1,819.3
Other long-term liabilities	Other long-term liabilities consist of the following: (In millions) As of As of Contingent consideration obligations $ 302.2 $ 200.0 Employee compensation and benefits 224.5 200.7 Other 389.0 249.4 Total other long-term liabilities $ 915.7 $ 650.1

Summary of Significant Accoun41

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)segment	Dec. 31, 2014USD ($)
Accounting Policies [Abstract]
Interest in subsidiary (less than given percentage)	100.00%
Number of reportable segments | segment	1
Payment terms of accounts receivable arising from product sales
Minimum term for accounts receivable	30 days
Maximum term for accounts receivable	90 days
Accumulated depreciation	$ 1,274.2	$ 1,186.4

Acquisitions Acquisitions (Deta

Acquisitions Acquisitions (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition [Line Items]
Contingent consideration		$ 36	$ 0	$ 274.5	$ 0
Convergence Pharmaceuticals
Business Acquisition [Line Items]
Cash portion of consideration	$ 200.1
Contingent consideration	274.5
Total purchase price	$ 474.6

Acquisitions Acquisitions (De43

Acquisitions Acquisitions (Details 1) - USD ($) $ in Thousands	Jun. 30, 2015	Feb. 12, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 2,154,341		$ 1,760,249
Convergence Pharmaceuticals
Business Acquisition [Line Items]
In-process research and development and other intangible assets		$ 424,600
Other intangible assets		7,600
Goodwill		128,300
Deferred tax liability		(84,900)
Other, net		(1,000)
Total purchase price		$ 474,600

Acquisitions Acquisitions (De44

Acquisitions Acquisitions (Details Textual) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Feb. 12, 2015
Business Acquisition [Line Items]
Contingent consideration		$ 36	$ 0	$ 274.5	$ 0
Convergence Pharmaceuticals
Business Acquisition [Line Items]
Cash portion of consideration	$ 200.1
Potential future milestone payments						$ 450
Contingent consideration	$ 274.5
Increase in the value of our estimated contingent consideration		36
Increase in goodwill		$ 36
Discount rate	2.00%
In-process research and development and other intangible assets						424.6
Convergence Pharmaceuticals | CNV1014802
Business Acquisition [Line Items]
Potential future milestone payments						350
Discount rate	11.00%
Remaining cost to complete CNV1014802						145
In-process research and development and other intangible assets						200
Convergence Pharmaceuticals | Neuropathic pain indications
Business Acquisition [Line Items]
Remaining cost to complete CNV1014802						415
In-process research and development and other intangible assets						$ 220

Reserves for Discounts and Al45

Reserves for Discounts and Allowances (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)
Analysis of the amount of, and change in, reserves
Balance as of December 31, 2014	$ 483.8
Current provisions relating to sales in current year	1,082.7
Adjustments relating to prior years	(27.5)
Payments/credits relating to sales in current year	(642.8)
Payments/credits relating to sales in prior years	(305.8)
Balance as of June 30, 2015	590.4
Discounts
Analysis of the amount of, and change in, reserves
Balance as of December 31, 2014	47.6
Current provisions relating to sales in current year	209.2
Adjustments relating to prior years	0.4
Payments/credits relating to sales in current year	(158)
Payments/credits relating to sales in prior years	(43.3)
Balance as of June 30, 2015	55.9
Contractual Adjustments
Analysis of the amount of, and change in, reserves
Balance as of December 31, 2014	387.1
Current provisions relating to sales in current year	854.4
Adjustments relating to prior years	(19.8)
Payments/credits relating to sales in current year	(483.9)
Payments/credits relating to sales in prior years	(254.7)
Balance as of June 30, 2015	483.1
Returns
Analysis of the amount of, and change in, reserves
Balance as of December 31, 2014	49.1
Current provisions relating to sales in current year	19.1
Adjustments relating to prior years	(8.1)
Payments/credits relating to sales in current year	(0.9)
Payments/credits relating to sales in prior years	(7.8)
Balance as of June 30, 2015	$ 51.4

Reserves for Discounts and Al46

Reserves for Discounts and Allowances (Details 1) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Summary of total product revenue reserves included in consolidated balance sheets
Total reserves	$ 590.4	$ 483.8
Reduction of accounts receivable
Summary of total product revenue reserves included in consolidated balance sheets
Total reserves	143.9	124.6
Component of accrued expenses and other
Summary of total product revenue reserves included in consolidated balance sheets
Total reserves	$ 446.5	$ 359.2

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Components of inventories
Raw materials	$ 173,200	$ 128,300
Work in process	516,700	511,500
Finished goods	175,800	164,200
Total inventory	$ 865,738	$ 804,022

Inventory Inventory (Details Te

Inventory Inventory (Details Textual) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventory, Various Programs, Gross	$ 35.8	$ 6.3

Intangible Assets and Goodwil49

Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Feb. 12, 2015	Dec. 31, 2014
Intangible assets
Total intangible assets, gross	$ 7,661,300		$ 7,661,300			$ 7,207,100
Accumulated Amortization	(3,366,500)		(3,366,500)			(3,178,600)
Intangible assets, net	4,294,791		4,294,791			4,028,507
Intangible Assets and Goodwill (Textual) [Abstract]
Amortization of acquired intangible assets	92,004	$ 116,826	187,907	$ 260,084
Accumulated impairment losses related to goodwill	0		0
Expected future amortization expense, 2015 (remaining six months)	185,500		185,500
Expected future amortization expense, 2016	312,500		312,500
Expected future amortization expense, 2017	285,800		285,800
Expected future amortization expense, 2018	281,600		281,600
Expected future amortization expense, 2019	270,600		270,600
Expected future amortization expense, 2020	263,800		263,800
Total	1,599,800		1,599,800
Out-licensed patents
Intangible assets
Cost	543,300		543,300			543,300
Accumulated Amortization	(493,900)		(493,900)			(481,700)
Net	49,400		$ 49,400			61,600
Impairment of out-licensed patent		$ 34,700
Out-licensed patents | Minimum
Intangible assets
Estimated life, (in years)			13 years
Out-licensed patents | Maximum
Intangible assets
Estimated life, (in years)			23 years
Developed technology
Intangible assets
Cost	3,005,300		$ 3,005,300			3,005,300
Accumulated Amortization	(2,492,100)		(2,492,100)			(2,396,800)
Net	513,200		$ 513,200			608,500
Developed technology | Minimum
Intangible assets
Estimated life, (in years)			15 years
Developed technology | Maximum
Intangible assets
Estimated life, (in years)			23 years
Developed technology | AVONEX
Intangible assets
Net	504,300		$ 504,300
Acquired and in-licensed rights and patents
Intangible assets
Cost	3,296,700		3,296,700			3,280,400
Accumulated Amortization	(380,500)		(380,500)			(300,100)
Net	2,916,200		$ 2,916,200			2,980,300
Acquired and in-licensed rights and patents | Minimum
Intangible assets
Estimated life, (in years)			3 years
Acquired and in-licensed rights and patents | Maximum
Intangible assets
Estimated life, (in years)			17 years
In-process research and development
Intangible assets
Indefinite lived intangible assets useful life
Cost and Net	752,000		$ 752,000			314,100
Accumulated Amortization	0		$ 0			0
Trademarks and trade names
Intangible assets
Indefinite lived intangible assets useful life
Cost and Net	64,000		$ 64,000			64,000
Accumulated Amortization	0		0			$ 0
Convergence Pharmaceuticals
Intangible assets
In-process research and development and other intangible assets					$ 424,600
TYSABRI product | Acquired and in-licensed rights and patents
Intangible assets
Net	$ 2,851,900		$ 2,851,900

Intangible Assets and Goodwil50

Intangible Assets and Goodwill (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Goodwill [Line Items]
Income tax benefit (expense)	$ 292,501	$ 268,521	$ 574,382	$ 446,935
Increase to goodwill			390,000
Summary of roll forward of the changes in goodwill
Goodwill, beginning of period			1,760,249
Other			4,100
Goodwill, end of period	$ 2,154,341		2,154,341
TECFIDERA | Fumapharm AG
Goodwill [Line Items]
Income tax benefit (expense)			38,300
Increase to goodwill			$ 300,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Assets:
Marketable debt securities	$ 3,188.4		$ 2,111.1
Fair Value, Measurements, Recurring
Assets:
Cash equivalents	974		716.3
Investments	6.8		6.9
Derivative contracts	100.5		72.7
Plan assets for deferred compensation	40.7		36.9
Total	4,310.4		2,943.9
Liabilities:
Derivative contracts	27.7		5.4
Contingent consideration obligations	495.6	$ 461.8	215.5	$ 279.1	$ 275.1	$ 280.9
Total	523.3		220.9
Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	1,198.1		1,063
Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	1,700.3		849.8
Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	290		198.3
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	0		0
Investments	6.8		6.9
Derivative contracts	0		0
Plan assets for deferred compensation	0		0
Total	6.8		6.9
Liabilities:
Derivative contracts	0		0
Contingent consideration obligations	0		0
Total	0		0
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	0		0
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	0		0
Quoted Prices in Active Markets, Level 1 | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	0		0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	974		716.3
Investments	0		0
Derivative contracts	100.5		72.7
Plan assets for deferred compensation	40.7		36.9
Total	4,303.6		2,937
Liabilities:
Derivative contracts	27.7		5.4
Contingent consideration obligations	0		0
Total	27.7		5.4
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	1,198.1		1,063
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	1,700.3		849.8
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	290		198.3
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Cash equivalents	0		0
Investments	0		0
Derivative contracts	0		0
Plan assets for deferred compensation	0		0
Total	0		0
Liabilities:
Derivative contracts	0		0
Contingent consideration obligations	495.6		215.5
Total	495.6		215.5
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Corporate debt securities
Assets:
Marketable debt securities	0		0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Government securities
Assets:
Marketable debt securities	0		0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Mortgage and other asset backed securities
Assets:
Marketable debt securities	$ 0		$ 0

Fair Value Measurements (Deta52

Fair Value Measurements (Details 1) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Notes payable, carrying value	$ 579.5	$ 585.2
Debt instruments, fair value	631.5	647.2
Notes Payable to Fumedica
Debt Instrument [Line Items]
Notes payable, fair value	10	12.6
Notes payable, carrying value	9.4	11.7
6.875% Senior Notes due 2018
Debt Instrument [Line Items]
Notes payable, fair value	621.5	634.6
Notes payable, carrying value	$ 570.1	$ 573.5

Fair Value Measurements (Deta53

Fair Value Measurements (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition, Contingent Consideration [Line Items]
Additions	$ 36,000	$ 0	$ 274,500	$ 0
Changes in fair value	(2,201)	4,019	5,643	3,220
Payments	0	0	0	(5,000)
Fair Value, Measurements, Recurring
Business Acquisition, Contingent Consideration [Line Items]
Fair value, beginning of period	461,800	275,100	215,500	280,900
Fair value, end of period	$ 495,600	$ 279,100	$ 495,600	$ 279,100

Fair Value Measurements (Deta54

Fair Value Measurements (Details Textual) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Feb. 12, 2015	Dec. 31, 2014
Business Acquisition, Contingent Consideration [Line Items]
Asset impairment charges				$ 0
Changes in valuation techniques				0
Contingent consideration obligations		$ 302.2		$ 302.2			$ 200
Contingent consideration		$ 36	$ 0	$ 274.5	$ 0
6.875% Senior Notes due 2018
Business Acquisition, Contingent Consideration [Line Items]
Stated rate on debt		6.875%		6.875%
Convergence Pharmaceuticals
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration	$ 274.5
Potential future milestone payments						$ 450
Discount rate	2.00%
In-process research and development and other intangible assets						$ 424.6

Financial Instruments (Details)

Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Marketable Debt and Equity Securities
Fair Value	$ 3,188.4	$ 2,111.1
Gross Unrealized Gains	1.7	0.7
Gross Unrealized Losses	(1.8)	(2.4)
Amortized Cost	3,188.5	2,112.8
Corporate debt securities Current
Marketable Debt and Equity Securities
Fair Value	375.9	370.4
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	(0.1)	(0.2)
Amortized Cost	375.9	370.6
Corporate debt securities Non-current
Marketable Debt and Equity Securities
Fair Value	822.2	692.6
Gross Unrealized Gains	0.4	0.2
Gross Unrealized Losses	(1.2)	(1.5)
Amortized Cost	823	693.9
Government securities Current
Marketable Debt and Equity Securities
Fair Value	710.5	269.9
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	(0.1)	(0.1)
Amortized Cost	710.5	270
Government securities Non-current
Marketable Debt and Equity Securities
Fair Value	989.8	579.9
Gross Unrealized Gains	0.9	0.3
Gross Unrealized Losses	(0.1)	(0.4)
Amortized Cost	989	580
Mortgage and other asset backed securities Current
Marketable Debt and Equity Securities
Fair Value	0.2	0.2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Amortized Cost	0.2	0.2
Mortgage and other asset backed securities Non-current
Marketable Debt and Equity Securities
Fair Value	289.8	198.1
Gross Unrealized Gains	0.2	0.2
Gross Unrealized Losses	(0.3)	(0.2)
Amortized Cost	289.9	198.1
Marketable equity securities
Marketable Debt and Equity Securities
Fair Value	6.8	6.9
Gross Unrealized Gains	1.1	1.2
Gross Unrealized Losses	0	(0.2)
Amortized Cost	$ 5.7	$ 5.9

Financial Instruments (Details

Financial Instruments (Details 1) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents
Cash equivalents	$ 974	$ 716.3
Commercial paper
Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents
Cash equivalents	38.8	54.2
Overnight reverse repurchase agreements
Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents
Cash equivalents	185	305
Money market funds
Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents
Cash equivalents	740.2	321.2
Short-term debt securities
Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents
Cash equivalents	$ 10	$ 35.9

Financial Instruments (Detail57

Financial Instruments (Details 2) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Summary of Contractual Maturities: Available-for-Sale Securities
Due in one year or less, estimated fair value	$ 1,086.6	$ 640.5
Due in one year or less, amortized cost	1,086.6	640.8
Due after one year through five years, Estimated Fair Value	1,954.4	1,343.7
Due after one year through five years, Amortized Cost	1,954.5	1,345.2
Due after five years, estimated fair value	147.4	126.9
Due after five years, amortized cost	147.4	126.8
Total available-for-sale securities, Fair Value	3,188.4	2,111.1
Total available-for-sale securities, Amortized Cost	$ 3,188.5	$ 2,112.8

Financial Instruments (Detail58

Financial Instruments (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds from maturities and sales	$ 601,900	$ 560,100	$ 975,517	$ 1,317,525
Realized gains	300	200	500	400
Realized losses	$ (500)	$ (100)	$ (800)	$ (200)

Financial Instruments (Detail59

Financial Instruments (Details Textual)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Original maturities of commercial paper and short-term debt securities	less than 90 days
Overnight reverse repurchase agreements, percent of total assets	1.10%	2.10%
Average maturity of marketable securities, months	17 months	15 months

Financial Instruments Financial

Financial Instruments Financial Instruments (Details Textual 2) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Strategic Investments
Business Acquisition [Line Items]
Strategic investment portfolio	$ 45.3	$ 47.8

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative Instruments (Textual) [Abstract]
Lower range of durations of foreign currency forward contracts			1 month		1 month
Higher range of durations of foreign currency forward contracts			18 months		15 months
Gain/Loss on fair value of foreign currency forward contracts	$ 63.1		$ 63.1		$ 72.1
Expected settlement time for contracts, in months			18 months
Net gains (losses) of other income (expense) related to foreign currency forward contracts	13.6	$ 2.4	$ 3.9	$ 3.8
Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	1,517		1,517		1,302.3
Not designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	472.4		472.4		365.2
Foreign Exchange Contract | Other current assets | Designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative asset, fair value, net	92.8		92.8		69.5
Foreign Exchange Contract | Other current assets | Not designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative asset, fair value, net	7.7		7.7		1.3
Foreign Exchange Contract | Investments and other assets | Designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative asset, fair value, net					1.9
Foreign Exchange Contract | Accrued expenses and other | Designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative liability, fair value, net	9.8		9.8
Foreign Exchange Contract | Accrued expenses and other | Not designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative liability, fair value, net	0.7		0.7		5.4
Foreign Exchange Contract | Other long-term liabilities | Designated as hedging instrument
Summary of Derivatives designated as Hedging Instruments
Derivative liability, fair value, net	17.2		17.2
Revenue | Foreign Exchange Contract
Derivative Instruments (Textual) [Abstract]
Net gains (losses) in product revenue for the settlement of certain effective cash flow hedge instruments	40.4	(5.2)	75.4	(10)
Other income (expense) | Foreign Exchange Contract
Derivative Instruments (Textual) [Abstract]
Net gains (losses) in earnings of Foreign currency forward contracts due to hedge ineffectiveness	1.2	$ (1)	3.4	$ (1.2)
Euro | Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	1,437.2		1,437.2		1,174.6
Canadian Dollar | Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	32.1		32.1		56.7
British Pound Sterling | Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	21.9		21.9		34.5
Japanese Yen | Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	15.5		15.5		16.6
Australian Dollar | Designated as hedging instrument
Derivative Instruments (Textual) [Abstract]
Aggregate notional amount	$ 10.3		$ 10.3		$ 19.9

Equity (Details)

Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation of equity attributable to non-controlling interests
NCI, beginning of period	$ 2,700	$ 4,400	$ 5,030	$ 600
Net income (loss) attributable to NCI, net of tax	(2,451)	8,626	(4,818)	8,398
Fair value of net assets and liabilities acquired and assigned to NCI	0	0	0	4,000
Distribution to noncontrolling interest		(9,100)		(9,100)
Translation adjustment and other	200	0	200	0
NCI, end of period	$ 421	$ 3,900	$ 421	$ 3,900

Equity (Details Textual)

Equity (Details Textual) - USD ($) $ in Thousands, shares in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Equity (Textual) [Abstract]
Equity increase during the period	$ 1,759,000
Common stock value authorized for repurchase	$ 5,000,000
Common stock shares authorized remaining or repurchase	1.3
Common stock shares repurchased	0.1	1.2
Purchase of treasury stock	$ 42,193	$ 336,905

Accumulated Other Comprehensi64

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Accumulated other comprehensive income [Line Items]
Accumulated other comprehensive income (loss), net of tax	$ (101,025)	$ (26,700)	$ (101,025)	$ (26,700)	$ (59,488)	$ (27,700)
Other comprehensive income loss before reclassifications			33,300	(2,500)
Amounts reclassified from accumulated other comprehensive income loss			(74,800)	3,500
Net current period other comprehensive income loss	(30,487)	(4,322)	(41,537)	1,066
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated other comprehensive income [Line Items]
Accumulated other comprehensive income (loss), net of tax	700	400	700	400	(400)	5,600
Other comprehensive income loss before reclassifications			900	1,400
Amounts reclassified from accumulated other comprehensive income loss			200	(6,600)
Net current period other comprehensive income loss			1,100	(5,200)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated other comprehensive income [Line Items]
Accumulated other comprehensive income (loss), net of tax	62,800	(7,100)	62,800	(7,100)	71,700	(23,700)
Other comprehensive income loss before reclassifications			66,100	6,500
Amounts reclassified from accumulated other comprehensive income loss			(75,000)	10,100
Net current period other comprehensive income loss			(8,900)	16,600
Accumulated Defined Benefit Plans Adjustment
Accumulated other comprehensive income [Line Items]
Accumulated other comprehensive income (loss), net of tax	(27,500)	(19,000)	(27,500)	(19,000)	(31,600)	(19,600)
Other comprehensive income loss before reclassifications			4,100	600
Amounts reclassified from accumulated other comprehensive income loss			0	0
Net current period other comprehensive income loss			4,100	600
Accumulated Translation Adjustment
Accumulated other comprehensive income [Line Items]
Accumulated other comprehensive income (loss), net of tax	$ (137,000)	$ (1,000)	(137,000)	(1,000)	$ (99,200)	$ 10,000
Other comprehensive income loss before reclassifications			(37,800)	(11,000)
Amounts reclassified from accumulated other comprehensive income loss			0	0
Net current period other comprehensive income loss			$ (37,800)	$ (11,000)

Accumulated Other Comprehensi65

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	$ (10,889)	$ 4,861	$ (25,875)	$ (740)
Income tax benefit (expense)	292,501	268,521	574,382	446,935
Product, net	(2,198,566)	(2,056,292)	(4,370,888)	(3,799,057)
Net income attributable to Biogen Inc.	927,276	714,506	1,749,817	1,194,462
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Biogen Inc.	40,100	700	74,800	(3,500)
Accumulated Net Unrealized Investment Gain (Loss) | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	(200)	10,100	(300)	10,200
Income tax benefit (expense)	100	(3,600)	100	(3,600)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax benefit (expense)	(200)	(500)	(400)	(100)
Product, net	$ (40,400)	$ (5,300)	$ (75,400)	$ (10,000)

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator:
Net income attributable to Biogen Inc	$ 927,276	$ 714,506	$ 1,749,817	$ 1,194,462
Weighted-average shares used in calculating:
Weighted average number of common shares outstanding	235,286	236,661	235,122	236,729
Effect of dilutive securities:
Dilutive potential common shares	400	700	600	900
Shares used in calculating diluted earnings per share	235,718	237,401	235,671	237,634
Stock options and employee stock purchase plan
Effect of dilutive securities:
Stock units	100	100	100	100
Time-vested restricted stock units
Effect of dilutive securities:
Stock units	200	400	300	500
Market stock units
Effect of dilutive securities:
Stock units	100	200	200	300

Share-Based Payments (Details)

Share-Based Payments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Expense included in consolidated statements of income
Subtotal	$ 48.3	$ 58.1	$ 139.3	$ 134.7
Capitalized share-based compensation costs	(2.2)	(2.6)	(5.6)	(5.2)
Share-based compensation expense included in total costs and expenses	46.1	55.5	133.7	129.5
Income tax effect	(12.9)	(16.5)	(39.6)	(38.8)
Research and development
Share-based Compensation Expense included in consolidated statements of income
Share-based compensation expense	22.1	24.5	57.5	53.9
Selling, general and administrative
Share-based Compensation Expense included in consolidated statements of income
Share-based compensation expense	26.2	33.6	81.8	80.8
Total share-based compensation expense, net of tax
Share-based Compensation Expense included in consolidated statements of income
Share-based compensation expense	$ 33.2	$ 39	$ 94.1	$ 90.7

Share-Based Payments (Details 1

Share-Based Payments (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Summary of share based compensation expense associated with different programs
Subtotal	$ 48.3	$ 58.1	$ 139.3	$ 134.7
Capitalized share-based compensation costs	(2.2)	(2.6)	(5.6)	(5.2)
Share-based compensation expense included in total costs and expenses	46.1	55.5	133.7	129.5
Market stock units
Summary of share based compensation expense associated with different programs
Share-based compensation expense	9.1	8.2	26.1	23.1
Time-vested restricted stock units
Summary of share based compensation expense associated with different programs
Share-based compensation expense	31.8	29.2	63.7	58.4
Cash settled performance shares
Summary of share based compensation expense associated with different programs
Share-based compensation expense	3.2	14	27	35.4
Performance units
Summary of share based compensation expense associated with different programs
Share-based compensation expense	1.2	4	14.4	10.3
Employee stock purchase plan
Summary of share based compensation expense associated with different programs
Share-based compensation expense	$ 3	$ 2.7	$ 8.1	$ 7.5

Share-Based Payments (Details 2

Share-Based Payments (Details 2) - shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Market stock units
Schedule of stock option grants
Stock units	179,000	222,000
Cash settled performance shares
Schedule of stock option grants
Stock units	115,000	180,000
Performance units
Schedule of stock option grants
Stock units	89,000	50,000
Time-vested restricted stock units
Schedule of stock option grants
Stock units	375,000	418,000

Share-Based Payments (Details T

Share-Based Payments (Details Textual) - shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee stock purchase plan maximum shares	6,200,000
Shares issued under ESPP	98,000	112,000

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation between the U.S. federal statutory tax rate and effective tax rate
Statutory rate	35.00%	35.00%	35.00%	35.00%
State taxes	0.40%	1.10%	0.00%	1.10%
Taxes on foreign earnings	(11.10%)	(8.70%)	(9.80%)	(8.50%)
Credits and net operating loss utilization	0.70%	0.70%	0.70%	0.90%
Purchased intangible assets	1.10%	1.20%	1.00%	1.30%
Manufacturing deduction	(2.10%)	(1.70%)	(1.80%)	(1.80%)
Permanent items	0.90%	0.40%	0.70%	0.40%
Other	0.40%	0.40%	0.30%	0.30%
Effective tax rate	23.90%	27.00%	24.70%	26.90%

Income Taxes (Details Textual)

Income Taxes (Details Textual) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Oct. 31, 2011	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015
Income Tax Contingency [Line Items]
Effective tax rate		23.90%	27.00%	24.70%	26.90%
Notice of assessment of corporate withholding tax including penalties and interest						$ 48.3
Net benefit for a previously unrecognized position		$ 24		$ 24
Tax Year 2007
Income Tax Contingency [Line Items]
Proposed deduction disallowance by tax authorities	$ 130
Tax Year 2008
Income Tax Contingency [Line Items]
Proposed deduction disallowance by tax authorities	130
Tax Year 2009
Income Tax Contingency [Line Items]
Proposed deduction disallowance by tax authorities	$ 130

Other Consolidated Financial 73

Other Consolidated Financial Statement Detail (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 28, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Prepaid taxes		$ 280,500		$ 280,500		$ 57,600
Accrued Expenses and Other
Current portion of contingent consideration obligations		493,500		493,500		265,500
Revenue-related rebates		590,400		590,400		483,800
Employee compensation and benefits		214,400		214,400		393,800
Royalties and licensing fees		161,900		161,900		172,400
Deferred revenue		62,500		62,500		120,900
Other		433,300		433,300		507,500
Total accrued expenses and other		1,812,099		1,812,099		1,819,334
Other Income (Expense), Net
Interest income		4,300	$ 2,400	7,600	$ 5,100
Interest expense		(5,800)	(7,100)	(12,500)	(14,700)
Gain (loss) on sales of investments, net		300	13,600	(1,400)	16,600
Foreign exchange gains (losses), net		(1,500)	(1,400)	(14,500)	(4,700)
Other, net		(8,200)	(2,600)	(5,100)	(3,000)
Business Acquisition [Line Items]
Contingent consideration		36,000	0	274,500	0
Other income (expense), net		(10,889)	$ 4,861	(25,875)	$ (740)
Liabilities, Noncurrent
Contingent consideration obligations		302,200		302,200		200,000
Employee related liabilities noncurrent		224,500		224,500		200,700
Other		389,000		389,000		249,400
Total other long-term liabilities		915,731		915,731		650,096
Convergence Pharmaceuticals
Business Acquisition [Line Items]
Cash portion of consideration	$ 200,100
Contingent consideration	274,500
Total purchase price	$ 474,600
Component of accrued expenses and other
Accrued Expenses and Other
Revenue-related rebates		$ 446,500		$ 446,500		$ 359,200

Other Consolidated Financial 74

Other Consolidated Financial Statement Detail Other Consolidated Financial Statement (Details Textual) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015EUR (€)	Dec. 31, 2014EUR (€)
Product Liability Contingency [Line Items]
Product, net	$ 2,198,566	$ 2,056,292	$ 4,370,888	$ 3,799,057
Italy
Product Liability Contingency [Line Items]
Reimbursement limit stated in the resolution		24 months
Product, net		$ 53,500
Proposed settlement | €						€ 35.6
Amount reserved for this matter | €					€ 75

Investments in Variable Inter75

Investments in Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Investment in Variable Interest Entities (Textual) [Abstract]
Research and development	$ 490,728	$ 447,273	$ 951,277	$ 976,157
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities	8,500		8,500		$ 7,900
Neurimmune
Investment in Variable Interest Entities (Textual) [Abstract]
Remaining potential development milestone payments and royalties on commercial sales under the terms of collaboration agreement			335,000
Expected milestone payment for initiation of a late stage clinical trial			60,000
Research and development	$ 35,000	$ 10,600	$ 47,800	$ 21,700

Collaborative and Other Relat76

Collaborative and Other Relationships Collaborative and Other Relationships - Equity Method Investments (Details) $ in Thousands, ₩ in Billions	1 Months Ended	3 Months Ended			6 Months Ended
	Feb. 29, 2012USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2013USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2015KRW (₩)	Jun. 30, 2014USD ($)	Jun. 30, 2015KRW (₩)	Dec. 31, 2014USD ($)	Dec. 31, 2014KRW (₩)	Feb. 29, 2012KRW (₩)
Schedule of Equity Method Investments [Line Items]
Recognized loss		$ (4,881)	$ (1,933)		$ (5,715)		$ (9,538)
Research and development		490,728	447,273		951,277		976,157
Revenue related to technical development and technology transfer services		55,566	61,864		107,596		151,965
Samsung Biosimilar Agreement [Member]
Schedule of Equity Method Investments [Line Items]
Contribution from Samsung to develop, manufacture and market biosimilar pharmaceuticals	$ 250,000										₩ 280.5
Variable interest entity, qualitative or quantitative information, ownership percentage	85.00%
Contribution from Biogen to develop, manufacture and market biosimilar pharmaceuticals	$ 45,000	$ 6,800			$ 6,800			₩ 7.5	$ 8,600	₩ 9.1	₩ 49.5
Percentage of stake in entity minimum	15.00%	10.00%			10.00%			10.00%			15.00%
Additional contribution made to Samsung Bioepis					$ 5,700	₩ 6.3
Percentage of stake in entity maximum	49.90%
Recognized loss		$ (4,900)	(1,900)		(5,700)		(9,500)
Research and development				$ 46,000
Additional milestone payment				$ 75,000
Expected profit share with Samsung Bioepis				50.00%
Revenue related to technical development and technology transfer services		$ 17,200	$ 12,300		$ 36,100		$ 36,500

Litigation (Details)

Litigation (Details)	3 Months Ended
	Jun. 30, 2014
Italy
Loss Contingencies [Line Items]
Reimbursement limit stated in the resolution	24 months

Commitments and Contingences (D

Commitments and Contingences (Details) - Fumapharm AG - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2006	Jun. 30, 2013
Business Acquisition, Contingent Consideration [Line Items]
Cash portion of consideration		$ 220
TECFIDERA
Business Acquisition, Contingent Consideration [Line Items]
Maximum contingent consideration in the form of development and approval milestones			$ 15
Four billion
Business Acquisition, Contingent Consideration [Line Items]
Cash portion of consideration	$ 250
Cumulative sales level	4,000
Five billion
Business Acquisition, Contingent Consideration [Line Items]
Cash portion of consideration	300
Cumulative sales level	5,000
Each additional one billion up to twenty billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level	20,000
One billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level	1,000
Three billion
Business Acquisition, Contingent Consideration [Line Items]
Cumulative sales level	$ 3,000

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies (Details 1) SFr in Millions	Jun. 30, 2015CHF (SFr)
Switzerland
Long-term Purchase Commitment [Line Items]
Land	SFr 65.1

Subsequent Events Subsequent 80

Subsequent Events Subsequent Events (Details) - USD ($) $ in Thousands	Jul. 15, 2015	Jul. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jul. 16, 2015	Jul. 02, 2015
Subsequent Event [Line Items]
Research and development			$ 490,728	$ 447,273	$ 951,277	$ 976,157
AGTC | Subsequent event
Subsequent Event [Line Items]
Research and development		$ 124,000
Purchase of common stock		30,000
Prepaid research and development								$ 58,400
Total licensing and fees		$ 35,600
Potential future milestone payments								1,000,000
Eisai | Subsequent event
Subsequent Event [Line Items]
Term of lease	10 years
Swedish Orphan Biovitrum | Subsequent event
Subsequent Event [Line Items]
Additional milestone payment							$ 10,000
Lead programs | AGTC | Subsequent event
Subsequent Event [Line Items]
Potential future milestone payments								472,500
Discovery programs | AGTC | Subsequent event
Subsequent Event [Line Items]
Potential future milestone payments								$ 592,500