Investments, Debt and Equity Securities [Abstract] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Collaboration Agreement [Abstract] Collaboration Agreement Schedule of Research and Development Arrangement, Contract to Perform for Others [Table] Schedule of Research and Development Arrangement, Contract to Perform for Others [Table] Type of Arrangement and Non-arrangement Transactions [Axis] Type of Arrangement and Non-arrangement Transactions [Axis] Arrangements and Non-arrangement Transactions [Domain] Arrangements and Non-arrangement Transactions [Domain] sales achievement - $200 million sales achievement - 200 million [Member] sales achievement - 200 million Research and Development Arrangement, Contract to Perform for Others, Type [Axis] Research and Development Arrangement, Contract to Perform for Others, Type [Axis] Research and Development Arrangement, Contract to Perform for Others, Type [Domain] Research and Development Arrangement, Contract to Perform for Others, Type [Domain] EYLEA Collaboration Agreement with Bayer HealthCare LLC [Member] Collaboration agreement with Bayer HealthCare LLC. PDGFR-beta PDGFR-beta outside the US [Member] PDGFR-beta outside the US Ang2 Ang2 [Member] Ang2 [Member] Collaboration Agreement [Line Items] Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Net profit (loss) from commercialization of products under collaboration agreement Net profit (loss) from commercialization of products under collaboration agreement Our share of profits/losses related to commercialization of products by our collaborator based on sales outside the United States. Under the terms of our collaboration agreement, we share profits/losses with our collaborator on commercialization of products. Revenue Recognition, Milestone Method, Revenue Recognized Revenue Recognition, Milestone Method, Revenue Recognized Reimbursement of Regeneron research and development expenses Research and Development Arrangement, Contract to Perform for Others, Compensation Earned Contracts Revenue Contracts Revenue Other Collaboration Revenue Other Collaboration Revenue Revenue realized from sharing of profits/losses on commercialized products, reimbursement of research and development expenses, and other transactions with our collaborator Bayer during the period. Inventory Disclosure [Abstract] Schedule of Inventory, Current Schedule of Inventory, Current [Table Text Block] Schedule of Available-for-sale Securities [Table] Classification of Investment [Axis] Classification of Investment [Axis] This element represents the general categories of investments, which may be classified as Unrestricted or Restricted. Classification of Investment [Domain] Classification of Investment [Domain] Provides general categories of investments for which information is required or determined to be disclosed. Unrestricted [Member] Unrestricted [Member] Investments whose use is not restricted in whole or in part, by contractual agreements or regulatory requirements. Restricted [Member] Restricted [Member] Investments whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Corporate Bond Securities [Member] Corporate Bond Securities [Member] U.S. government and government agency obligations US Treasury and Government [Member] Municipal bonds Municipal Bonds [Member] Commercial Paper [Member] Commercial Paper [Member] Certificates of Deposit [Member] Certificates of Deposit [Member] Equity Securities Equity Securities [Member] Schedule of Available-for-sale Securities [Line Items] Payments to Acquire Marketable Securities Payments to Acquire Marketable Securities Amortized Cost Basis Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Securities Available-for-sale Securities Available-for-sale Securities, Debt Maturities, Fair Value [Abstract] Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Maturities within one year Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Maturities after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Total Available-for-sale Securities, Debt Securities Continuous Unrealized Loss Position, Fair Value [Abstract] Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] Fair Value - Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Fair Value - 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Fair Value - Total Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Continuous Unrealized Loss Position, Aggregate Losses [Abstract] Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract] Unrealized Loss - Less than 12 months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Unrealized Loss - 12 Months or Greater Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Unrealized Loss - Total Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Available-for-sale Securities Available-for-sale Securities [Table Text Block] Marketable Securities, Based on Contractual Maturity Dates Investments Classified by Contractual Maturity Date [Table Text Block] Fair Value and Unrealized Losses of Marketable Securities Schedule of Unrealized Loss on Investments [Table Text Block] Document And Entity Information [Abstract] -- None. No documentation exists for this element. -- Entities [Table] Class of Stock [Axis] Class of Stock [Domain] Common Stock Common Stock [Member] Class A Stock Common Class A [Member] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast [Member] Scenario, Forecast [Member] PDGF PDGF [Member] PDGF [Member] Praluent, sarilumab, and dupilumab Praluent and sarilumab [Member] Praluent and sarilumab [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Research and Development Arrangement Contract to Perform for Others by Product [Axis] Research and Development Arrangement Contract to Perform for Others by Product [Domain] Research and Development Arrangement Contract to Perform for Others by Product [Domain] [Domain] for Research and Development Arrangement Contract to Perform for Others by Product [Axis] ZALTRAP Agreement Aflibercept Agreement [Member] In September 2003, the Company entered into a collaboration agreement (the Aflibercept Agreement) with Aventis Pharmaceuticals Inc. (predecessor to Sanofi), to jointly develop and commercialize aflibercept. Antibody Collaboration Antibody Collaboration [Member] In November 2007, the Company entered into a global, strategic collaboration (the Antibody Collaboration) with Sanofi to discover, develop, and commercialize fully human monoclonal antibodies. IO Agreement IO Agreement [Member] IO Agreement Immuno-oncology Agreement Immuno-oncology Agreement [Member] Immuno-oncology Agreement Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Deferred revenue, revenue recognized Deferred Revenue, Revenue Recognized Other Income Other Income Recognition of Deferred Revenue Recognition of Deferred Revenue Annual funding maximum of research activities per amended agreement Annual funding maximum of research activities per amended agreement The maximum annual amount of funding for research activities through 2017 per the amended agreement. Revenue from Related Parties Revenue from Related Parties Percentage of Trial Costs borne by collaborating party Percentage of Trial Costs borne by collaborating party The percentage of subsequent Shared Phase 3 Trial costs borne by the collaborating party upon receipt of the first positive Phase 3 trial results for a co-developed drug candidate. Percentage of Trial Costs borne by entity Percentage of Trial Costs borne by entity The percentage of subsequent Shared Phase 3 Trial costs borne by the Company upon receipt of the first positive Phase 3 trial results for a co-developed drug candidate. Research and development Research and Development Expense Annual Funding Maximum of Research Activities Per Agreement Annual Funding Maximum of Research Activities Per Agreement The maximum amount of cost reimbursement the Company will receive on a annual basis. Deferred Revenue, Additions Deferred Revenue, Additions Research and Development [Abstract] Adicet Bio [Member] Adicet Bio [Member] Adicet Bio [Member] Research and Development Arrangement, Contract to Perform for Others [Line Items] Research and Development Arrangement, Contract to Perform for Others [Line Items] Upfront Payment Made Upfront Payment Made Upfront payment made under a collaboration agreement. Period over which the Company has obligation Period over which we have obligation Period over which the Company has the obligation to provide research funding. Collaboration Agreement with Bayer Revenue based on percentage of annual sales in Japan Revenue based on percentage of annual sales in Japan The percentage on annual sales in Japan that the Company is entitled to receive, subject to certain potential adjustments. Levels of twelve month sales at which sales milestone payments were received - 200 million Levels of twelve months sales at which sales milestone payments were received - 200 million In connection with a November 2013 agreement, the Company received additional sales milestone payments if twelve-month sales of specific commercial supplies of EYLEA outside the U.S. achieve certain specified levels up to this level. Period for Achieving Sales Target for Milestone Payment, Rolling Basis Period for Achieving Sales Target for Milestone Payment, Rolling Basis Period for Achieving Sales Target for Milestone Payment, Rolling Basis Earnings Per Share [Abstract] Net Income Per Share Earnings Per Share [Text Block] Revenues [Abstract] Revenue Recognition, Revenue Reductions [Policy Text Block] Revenue Recognition, Revenue Reductions [Policy Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Line Items] Statement [Line Items] Liabilities and Equity [Abstract] Stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common Stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common Stock, shares authorized (in shares) Common Stock, Shares Authorized Common Stock, shares issued (in shares) Common Stock, Shares, Issued Common Stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Treasury Stock, shares outstanding (in shares) Treasury Stock, Shares Risks and Uncertainties [Abstract] Statement [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Loss Contingency, Damages Sought, Value per unit Loss Contingency, Damages Sought, per unit produced. Loss Contingency, Damages Sought, per unit produced. Loss Contingency, Damages Sought, Value Loss Contingency, Damages Sought, Value PDGFR-beta outside the US [Member] Percentage of global development cost to be paid by the collaboration partner under the collaboration Percentage of global development cost to be paid by the collaboration partner under the collaboration Percentage of global development cost to be paid by the collaboration partner under the collaboration Percentage of development cost for the territory outside the United States to be paid for under the collaboration Percentage of development cost for the territory outside the United States previously required to be paid for under the collaboration Percentage of development cost for the territory outside the United States previously required to be paid for under the collaboration. Deferred Revenue, Additions New Accounting Pronouncements and Changes in Accounting Principles [Abstract] New Accounting Pronouncement, Early Adoption [Table] New Accounting Pronouncement, Early Adoption [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-09 Accounting Standards Update 2016-09 [Member] Accounting Standards Update 2016-09 [Member] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] Early adoption New Accounting Pronouncement, Early Adoption, Effect [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] New Accounting Pronouncement, Early Adoption [Line Items] New Accounting Pronouncement, Early Adoption [Line Items] Excess tax benefit from stock-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Organization, Consolidation and Presentation of Financial Statements [Abstract] Interim Financial Statements Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Legal Matters Legal Matters and Contingencies [Text Block] Fair Value Disclosures [Abstract] Fair Value Transfer, Policy [Policy Text Block] Fair Value Transfer, Policy [Policy Text Block] Collaboration Agreements Collaborative Arrangement Disclosure [Text Block] Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Warrant Transactions [Member] Warrant Transactions [Member] Warrant transactions entered into in connection with the offering of the convertible senior notes. Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Accrued capital expenditures Accrued Capital Expenditures Carrying value as of the balance sheet date of obligations incurred and payable for purchases of fixed assets. Included in accounts payable and accrued expenses. Accounts Payable, Other Accounts Payable, Other Other Liabilities, Fair Value Disclosure Other Liabilities, Fair Value Disclosure Facility lease obligation recognized during the period Facility lease obligation recognized during the period The facility lease obligation recognized during the period. Marketable Securities, Unrealized Gain (Loss) Marketable Securities, Unrealized Gain (Loss) Class A Stock Common Stock ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Marketable securities Marketable Securities, Current Accounts receivable - trade, net Accounts Receivable, Net, Current Accounts Receivable from Sanofi Accounts Receivable, Related Parties, Current Accounts receivable from Bayer Accounts and Notes Receivable, Net Inventories Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Marketable securities Marketable Securities, Noncurrent Property, plant, and equipment, net Property, Plant and Equipment, Net Deferred tax assets Deferred Tax Assets, Net, Noncurrent Other assets Other Assets, Noncurrent Total assets Assets LIABILITIES and STOCKHOLDERS' EQUITY Current liabilities: Liabilities, Current [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities, Current Deferred revenue from Sanofi, current portion Deferred Revenue From Related Party Current The current portion of deferred revenue from related parties as of balance sheet date. Current deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP. Deferred revenue - other, current portion Deferred Revenue, Current Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current Deferred revenue from Sanofi Deferred Revenue From Related Party Noncurrent The noncurrent portion of deferred revenue from related parties as of balance sheet date. Noncurrent deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP. Deferred Revenue - other Deferred Revenue, Noncurrent Facility lease obligations Facility lease obligations noncurrent Represents the noncurrent portion of a lease liability. In connection with the application of FASB authoritative guidance to the Company's lease of newly constructed facilities, the Company is deemed, in substance, to be the owner of the landlord's building; therefore, costs of constructing the facilities that the landlord incurred and reimbursements from the Company's landlord for tenant improvement costs were capitalized, offset by a corresponding lease obligation. Other long-term liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Preferred Stock Preferred Stock, Value, Issued Common stock Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive (loss) income Accumulated Other Comprehensive Income (Loss), Net of Tax Treasury stock Treasury Stock, Value Total stockholders' equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders' equity Liabilities and Equity Statement of Cash Flows Cash Flow, Supplemental Disclosures [Text Block] Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Mitsubishi Tanabe Pharma Corporation (MTPC) Mitsubishi Tanabe Pharma Corporation (MTPC) [Member] Mitsubishi Tanabe Pharma Corporation (MTPC) [Member] Collaborative Arrangement Collaborative Arrangement [Member] Payment [Axis] Payment [Axis] Payment [Axis] Payment [Domain] Payment [Domain] [Domain] for Payment [Axis] First Payment [Member] First Payment [Member] First Payment [Member] Second Payment [Member] Second Payment [Member] Second Payment [Member] Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Product Sales and Concentration Risk [Text Block] Product Sales and Concentration Risk [Text Block] Product Sales and Concentration Risk Disclosure [Text Block] Legal Costs, Policy [Policy Text Block] Legal Costs, Policy [Policy Text Block] Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Available-for-sale Securities [Member] Available-for-sale Securities [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Total income tax expense (benefit) Income Tax Expense (Benefit) Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Fair Value Measurements, Recurring and Nonrecurring [Table] Mitsubishi Tanabe Pharma Corporation (MTPC) [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Estimate of Fair Value Measurement [Member] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Measured on a recurring basis Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible senior notes Convertible Debt [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Proceeds from Sale and Maturity of Marketable Securities Proceeds from Sale and Maturity of Marketable Securities Other than Temporary Impairment Losses, Investments Other than Temporary Impairment Losses, Investments Convertible Debt Convertible Debt Available-for-sale marketable securities: Available-for-sale Securities [Abstract] U.S. government and government agency obligations U S Government Obligations Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. This item represents available-for-sale securities which consist of investments in U.S. government and government agency obligations neither classified as trading or held-to-maturity securities. Corporate bonds Financial Instruments, Owned, Corporate Debt, at Fair Value Municipal bonds Municipal Debt Securities, at Carrying Value Commercial Paper Commercial Paper, at Carrying Value Certificates of Deposit, at Carrying Value Certificates of Deposit, at Carrying Value Equity securities Available-for-sale Securities, Equity Securities Total fair value of available-for-sale marketable securities Convertible Debt [Abstract] Convertible Debt [Abstract] Interest rate, stated percentage Debt Instrument, Interest Rate, Stated Percentage Fair value of the outstanding notes Convertible Debt, Fair Value Disclosures Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss) Attributable to Parent Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Non-cash compensation expense Share-based Compensation Other non-cash charges and expenses, net Other Noncash Income (Expense) Increase (Decrease) in Deferred Income Taxes Increase (Decrease) in Deferred Income Taxes Changes in assets and liabilites Increase (Decrease) in Operating Capital [Abstract] Increase in Sanofi, Bayer, and trade accounts receivable Increase (Decrease) in Accounts Receivable Increase in Inventories Increase (Decrease) in Inventories Decrease (increase) in prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase in deferred revenue Increase (Decrease) in Deferred Revenue Increase in accounts payable, accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Total adjustments Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of marketable securities Sales or maturities of marketable securities Capital expenditures Payments to Acquire Productive Assets Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds in connection with facility lease obligations Proceeds from (Repayments of) Long-term Debt and Capital Securities Repayments of convertible senior notes Repayments of Convertible Debt Payments in connection with deduction of outstanding warrants Payments for Repurchase of Warrants Proceeds from issuance of Common Stock Proceeds from Issuance of Common Stock Payments in connection with Common Stock tendered for employee tax obligations Payments Related to Tax Withholding for Share-based Compensation Net cash used in by financing activities Net Cash Provided by (Used in) Financing Activities Net increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Income Taxes Income Tax Disclosure [Text Block] Collaboration revenue with related party Schedule of Related Party Transactions [Table Text Block] Collaboration revenue Collaboration revenue [Table Text Block] Summary of collaboration revenue [Table Text Block] Collaboration Agreements [Abstract] Collaboration Agreements [Abstract] Intella Therapeutics [Member] Intella Therapeutics [Member] Intella Therapeutics [Member] Project [Axis] Project [Axis] Project [Domain] Project [Domain] Collaboration Agreement, Number of Targets Company May Have Rights To Collaboration Agreement, Number of Targets Company Has Rights To Collaboration Agreement, Maximum Number of Targets Company May Have Rights To Collaboration Agreement, Extension Period Collaboration Agreement, Extension Period Collaboration Agreement, Extension Period Upon The Company Making A One-time Payment. Investment obligation Investment obligation The Company's maximum obligation to purchase common stock. Shares of Common Stock Purchased Shares of Common Stock Purchased The number of shares issued of the Company's Common Stock purchased in connection with a collaboration agreement. Inventory Inventory Disclosure [Text Block] Payables and Accruals [Abstract] Accounts Payable and Accrued Expenses Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Inventory Write-down Inventory Write-down Raw materials Inventory, Raw Materials, Net of Reserves Work in process Inventory, Work in Process, Net of Reserves Finished goods Inventory, Finished Goods, Net of Reserves Deferred costs Other Inventory, Net of Reserves Total Inventories Sales Related Deductions Activity Schedule of Sales Related Deductions Activity [Table Text Block] Tabular disclosure of the activity of sales-related deductions during the period, which may include rebates and chargebacks, and distributor-related fees. Accounts Payable and Accrued Liabilities, Current [Abstract] Accounts payable Accounts Payable, Trade, Current Accrued payroll and related costs Employee-related Liabilities, Current Accrued clinical trial expense Accrued Clinical Trial Expense Current Carrying value as of the balance sheet date of obligations incurred (and for which invoices have not been received) in connection with clinical trials. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued sales-related charges, deductions and royalties Accrued sales-related charges, deductions and royalties Carrying value as of the balance sheet date of sales-related charges, deductions and obligations incurred through that date and accrual for royalties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Taxes Payable, Current Taxes Payable, Current Other accrued expenses and liabilities Other Accrued Liabilities, Current Accounts payable and accrued expenses Basic and Diluted Net Income (Loss) Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Antidilutive Securities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Statement of Comprehensive Income [Abstract] Income Statement [Abstract] Income Statement [Abstract] Revenues: Net product sales Sales Revenue, Goods, Net Sanofi collaboration revenue Bayer Collaboration Revenue Other revenue Other Revenue, Net Total revenues Revenues Expenses: Costs and Expenses [Abstract] Selling, general, and administrative Selling, General and Administrative Expense Cost of goods sold Cost of Goods Sold Cost of collaboration and contract manufacturing Cost of manufacturing Total cost related to third-party royalties the Company is obligated to pay based on sales of commercial product by the Company’s collaborators, as well as costs in connection with producing commercial supplies for the Company’s collaborators and others. Total expenses Costs and Expenses Income from operations Operating Income (Loss) Other income (expense): Nonoperating Income (Expense) [Abstract] Investment income Investment Income, Nonoperating Interest and other expense, net Other Expenses Nonoperating Income (Expense) Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax expense Net income per share - basic Earnings Per Share, Basic Net income per share - diluted Earnings Per Share, Diluted Weighted average shares outstanding - basic Weighted Average Number of Shares Outstanding, Basic Weighted average shares outstanding - diluted Weighted Average Number of Shares Outstanding, Diluted Statements of Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized loss on marketable securities, net of tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Ang2 Antibody [Member] Ang2 Antibody [Member] Ang2 Antibody [Member] Future development milestone payment the Company is eligible to receive Future development milestone payment the Company is eligible to receive Future development milestone payment the Company is eligible to receive. Interest on Convertible Debt, Net of Tax Interest on Convertible Debt, Net of Tax Net Income (Loss) Available to Common Stockholders, Diluted Net Income (Loss) Available to Common Stockholders, Diluted Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Effect of dilutive securities (in shares): Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Stock options Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Restricted stock Incremental Common Shares Attributable To Nonvested Restricted Shares Nonvested equity-based payment awards that result in incremental common shares. Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Warrants Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Dilutive potential shares Weighted Average Number Diluted Shares Outstanding Adjustment Weighted average shares - diluted (in shares) Earnings Per Share, Basic and Diluted [Abstract] Net income per share - diluted (in dollars per share) Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Stock options Employee Stock Option [Member] Restricted Stock [Member] Restricted Stock [Member] Convertible senior notes Convertible Debt Securities [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Weighted average number of shares Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Debt Disclosure [Abstract] Debt Disclosure [Text Block] Debt Disclosure [Text Block] Schedule of assets measured at fair value on a recurring basis Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Teva Pharmaceuticals [Member] Teva Pharmaceuticals [Member] Teva Pharmaceuticals Collaboration Agreement Aggregate future development milestone payments the Company is eligible to receive Aggregate future development milestone payments the Company is eligible to receive Aggregate future development milestone payments the Company is eligible to receive. Sales based contingent consideration Aggregate future sales based milestone payments the Company is eligible to receive. Aggregate future sales based milestone payments the Company is eligible to receive. Description of New Accounting Pronouncements Not yet Adopted [Text Block] Description of New Accounting Pronouncements Not yet Adopted [Text Block] November 2015 Warrant Agreement November 2015 Agreement [Member] November 2015 Agreement [Member] February 2016 Warrant Agreement February 2016 Agreement [Member] February 2016 Agreement [Member] November 2014 Warrant Agreement November 2014 Warrant Agreement [Member] November 2014 Warrant Agreement [Member] Scenario [Axis] Credit Facility [Domain] Credit Facility [Domain] Debt Conversion Debt Conversion The principal amount of convertible notes that were settled for previously surrendered conversions. Stock Issued During Period, Shares, New Issues Stock Issued During Period, Shares, New Issues Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments Treasury Stock, Shares Gains (Losses) on Extinguishment of Debt Gains (Losses) on Extinguishment of Debt Treasury Stock, Value Maximum reduction of warrants held by warrant holder Maximum reduction of warrants held by warrant holder Maximum reduction of warrants held by warrant holder pursuant the agreement. Limit price per share for warrant holders to close out hedge position Limit price per share for warrant holders to close out hedge position Limit price per share for warrant holders to close out hedge position pursuant to the agreement. Adjustments to Additional Paid in Capital, Warrant Issued Adjustments to Additional Paid in Capital, Warrant Issued Reduction of number of warrants Reduction of number of warrants Reduction of number of warrants Warrant outstanding balance warrants outstanding Number of warrants outstanding Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Expiration Period Credit facility term The term of the Company's credit facility. Line of Credit Facility, Fair Value of Amount Outstanding Line of Credit Facility, Fair Value of Amount Outstanding Revenue Disclosure [Table] Revenue Disclosure [Table] EYLEA EYLEA Net Product Sales [Member] Revenue during the period derived from a specified product line (EYLEA), after deducting applicable provisions for discounts, returns, rebates, chargebacks, distribution fees, and other sales-related deductions. ARCALYST Arcalyst Net Product Sales [Member] Revenue during the period derived from a specified product line (ARCALYST), after deducting applicable provisions for discounts, returns, rebates, chargebacks, distribution fees, and other sales-related deductions. Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Valuation Allowances and Reserves [Domain] Rebates and Chargebacks Rebates and Chargebacks [Member] A valuation allowance for rebates and chargebacks under governmental programs (including Medicaid), which are netted against revenue from product sales. Distribution Related Fees Distribution Related Fees [Member] A valuation allowance for distribution-related fees which are netted against revenue from product sales. Other Sales Related Deductions Other Sales Related Deductions [Member] A valuation allowance for other sales-related deductions which are netted against revenue from product sales. Revenue Disclosure [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Activity of Sales Related Deductions [Roll Forward] Movement in Valuation Allowances and Reserves [Roll Forward] Balance Valuation Allowances and Reserves, Balance Provision related to current period sales Valuation Allowances and Reserves, Charged to Other Accounts Credits/payments Valuation Allowances and Reserves, Deductions