-Network: (00 - Document - Document and Company Information)

-Document and Entity Information [Abstract] {ID1}

Entity Registrant Name {ID2}

Entity Central Index Key {ID3}

Document Type {ID4}

Document Period End Date {ID5}

Amendment Flag {ID6}

Amendment Description {ID7}

Current Fiscal Year End Date {ID8}

Entity Well-known Seasoned Issuer {ID9}

Entity Voluntary Filers {ID10}

Entity Current Reporting Status {ID11}

Entity Filer Category {ID12}

Entity Public Float {ID13}

Entity Common Stock, Shares Outstanding {ID14}

-Network: (01 - Statement - Consolidated Statements of Income)

-Statements of Income [Abstract] {ID15}

-Statement [Table] {ID16}

-Statement [Line Items] {ID17}

-Revenues: {ID18}

Product {ID19}

Unconsolidated joint business {ID20}

Other revenues {ID21}

Total revenues {ID22}

-Costs and expenses: {ID23}

Cost of sales, excluding amortization of acquired intangible assets {ID24}

Research and development {ID25}

Selling, general and administrative {ID26}

Collaboration profit sharing {ID27}

Amortization of acquired intangible assets {ID28}

Acquired in-process research and development {ID29}

Total costs and expenses {ID30}

Income from operations {ID31}

Other income (expense), net {ID32}

Income before income tax expense {ID33}

Income tax expense {ID34}

Net income {ID35}

Net income attributable to noncontrolling interest, net of tax {ID36}

Net income attributable to Biogen Idec Inc. {ID37}

Basic earnings per share attributable to Biogen Idec Inc. {ID38}

Diluted earnings per share attributable to Biogen Idec Inc. {ID39}

-Weighted-average shares used in calculating: {ID40}

Basic earnings per share attributable to Biogen Idec Inc. {ID41}

Diluted earnings per share attributable to Biogen Idec Inc. {ID42}

-Network: (02 - Statement - Consolidated Balance Sheets)

-Balance Sheets [Abstract] {ID43}

-Statement [Table] {ID44}

-Statement [Line Items] {ID45}

-ASSETS {ID46}

-Current assets: {ID47}

Cash and cash equivalents {ID48}

Marketable securities {ID49}

Collateral received for loaned securities {ID50}

Accounts receivable, net {ID51}

Due from unconsolidated joint business {ID52}

Loaned securities {ID53}

Inventory {ID54}

Other current assets {ID55}

Total current assets {ID56}

Marketable securities {ID57}

Property, plant and equipment, net {ID58}

Intangible assets, net {ID59}

Goodwill {ID60}

Investments and other assets {ID61}

Total assets {ID62}

-LIABILITIES AND SHAREHOLDERS' EQUITY {ID63}

-Current liabilities: {ID64}

Collateral payable on loaned securities {ID65}

Accounts payable {ID66}

Taxes payable {ID67}

Accrued expenses and other {ID68}

Current portion of notes payable and line of credit {ID69}

Total current liabilities {ID70}

Notes payable and line of credit {ID71}

Long-term deferred tax liability {ID72}

Other long-term liabilities {ID73}

Total liabilities {ID74}

Commitments and contingencies {ID75}

-Equity: {ID76}

Preferred stock, par value $0.001 per share {ID77}

Common stock, par value $0.0005 per share {ID78}

Additional paid-in capital {ID79}

Accumulated other comprehensive income (loss) {ID80}

Retained earnings {ID81}

Treasury stock, at cost {ID82}

Total Biogen Idec Inc. shareholders' equity {ID83}

Noncontrolling interest {ID84}

Total equity {ID85}

Total liabilities and equity {ID86}

-Network: (021 - Statement - Consolidated Balance Sheets (Parenthetical))

-Balance Sheets (Parenthetical) [Abstract] {ID87}

-Statement [Table] {ID88}

-Statement [Line Items] {ID89}

Preferred stock, par value {ID90}

Common stock, par value {ID91}

-Network: (03 - Statement - Consolidated Statements of Cash Flows)

-Statements of Cash Flows [Abstract] {ID92}

-Statement [Table] {ID93}

-Statement [Line Items] {ID94}

-Cash flows from operating activities: {ID95}

Net income {ID96}

-Adjustments to reconcile net income to net cash flows from operating activities: {ID97}

Depreciation and amortization of property, plant and equipment and intangible assets {ID98}

Acquired in-process research and development {ID99}

Share-based compensation {ID100}

Non-cash interest (income) expense and foreign exchange remeasurement loss (gain), net {ID101}

Deferred income taxes {ID102}

Realized gain on sale of marketable securities and strategic investments {ID103}

Write-down of inventory to net realizable value {ID104}

Impairment of marketable securities, investments and other assets {ID105}

Excess tax benefit from stock options {ID106}

-Changes in operating assets and liabilities, net: {ID107}

Accounts receivable {ID108}

Due from unconsolidated joint business {ID109}

Inventory {ID110}

Other assets {ID111}

Accrued expenses and other current liabilities {ID112}

Other liabilities and taxes payable {ID113}

Net cash flows provided by operating activities {ID114}

-Cash flows from investing activities: {ID115}

Purchases of marketable securities {ID116}

Proceeds from sales and maturities of marketable securities {ID117}

Collateral received under securities lending {ID118}

Acquisitions, net of cash acquired {ID119}

Purchases of property, plant and equipment {ID120}

Purchases of other investments {ID121}

Proceeds from the sale of a strategic equity investment {ID122}

Net cash flows (used in) provided by investing activities {ID123}

-Cash flows from financing activities: {ID124}

Purchase of treasury stock {ID125}

Proceeds from issuance of stock for share-based compensation arrangements {ID126}

Change in cash overdraft {ID127}

Excess tax benefit from stock options {ID128}

Proceeds from borrowings {ID129}

Repayment of borrowings {ID130}

Obligation under securities lending {ID131}

Net cash flows used in financing activities {ID132}

Net increase (decrease) in cash and cash equivalents {ID133}

Effect of exchange rate changes on cash and cash equivalents {ID134}

Cash and cash equivalents, beginning of the period {ID135}

Cash and cash equivalents, end of the period {ID136}

-Network: (0601 - Disclosure - Business Overview)

-Business Overview [Abstract] {ID137}

Business Overview {ID138}

-Network: (0602 - Disclosure - Inventory)

-Inventory [Abstract] {ID139}

Inventory {ID140}

-Network: (0603 - Disclosure - Revenue Recognition)

-Revenue Recognition [Abstract] {ID141}

Revenue Recognition {ID142}

-Network: (0604 - Disclosure - Intangible Assets and Goodwill)

-Intangible Assets and Goodwill [Abstract] {ID143}

Intangible Assets and Goodwill {ID144}

-Network: (0605 - Disclosure - Fair Value Measurements)

-Fair Value Measurements [Abstract] {ID145}

Fair Value Measurements {ID146}

-Network: (0606 - Disclosure - Financial Instruments)

-Financial Instruments [Abstract] {ID147}

Financial Instruments {ID148}

-Network: (0607 - Disclosure - Property Plant and Equipment)

-Property Plant and Equipment Disclosure [Abstract] {ID149}

Property, Plant and Equipment {ID150}

-Network: (0608 - Disclosure - Equity)

-Equity Note Disclosure [Abstract] {ID151}

Equity {ID152}

-Network: (0609 - Disclosure - Earnings per Share)

-Earnings per Share Disclosure [Abstract] {ID153}

Earnings per Share {ID154}

-Network: (0610 - Disclosure - Share Based Payments)

-Share-Based Payments [Abstract] {ID155}

Share-Based Payments {ID156}

-Network: (0611 - Disclosure - Income Taxes)

-Income Taxes [Abstract] {ID157}

Income Taxes {ID158}

-Network: (0612 - Disclosure - Other Income (Expense), Net)

-Other Income (Expense), Net [Abstract] {ID159}

Other Income (Expense), Net {ID160}

-Network: (0613 - Disclosure - Collaborations)

-Collaborations [Abstract] {ID161}

Collaborations {ID162}

-Network: (0614 - Disclosure - Litigation)

-Litigation [Abstract] {ID163}

Litigation {ID164}

-Network: (0615 - Disclosure - Segment Information)

-Segment Information [Abstract] {ID165}

Segment Information {ID166}

-Network: (0616 - Disclosure - New Accounting Pronouncements)

-New Accounting Pronouncements [Abstract] {ID167}

New Accounting Pronouncements {ID168}

Biogen Idec Inc. XBRL Taxonomy Presentation Networks