Abingworth LLP [Member] Abingworth LLP [Member] Abingworth LLP Accounting Policies [Abstract] Accounting Policies [Abstract] Accounting Standards Update 2015-03 [Member] Accounting Standards Update 2015-03 Accounting Standards Update 2015-17 [Member] Accounting Standards Update 2015-17 Accounting Standards Update 2016-09 [Member] Accounting Standards Update 2016-09 [Member] ASU No. 2016-09 Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts Payable and Accrued Liabilities [Line Items] Accounts Payable and Accrued Liabilities [Line Items] Accounts Payable and Accrued Liabilities [Line Items] Accounts Payable and Accrued Liabilities [Table] Accounts Payable and Accrued Liabilities [Table] Accounts Payable and Accrued Liabilities [Table] Accounts Payable, Current Accounts payable Accounts Receivable Credit Period Accounts Receivable Credit Period Trade receivables, credit period Accounts Receivable, Gross, Current Gross trade accounts receivable Accounts Receivable [Member] Accounts Receivable Accounts Receivable, Net, Current Accounts receivable, net Accounts receivable, net Discloses the breakout of accrued expenses and other liabilities that are not individually material for a separate caption on the statement of financial position between the current portion (payable within 12 months of year end or the operating cycle) and non-current (payable after 12 months from year end). Accrued Expenses and Other Liabilities Disclosure [Text Block] Accrued Expenses and Other Current Liabilities Accrued Liabilities and Other Liabilities Accrued expenses and other current liabilities Total accrued expenses and other current liabilities Accrued Liabilities Sales Allowances Current Accrued Liabilities Sales Allowances Current Accrued revenue allowances Accrued Marketing Costs, Current Sales and marketing accruals Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated depreciation and amortization Additional Paid in Capital, Common Stock Additional paid-in capital Additional Paid-in Capital [Member] Additional Paid-in Capital Additional Percentage Interest Rate Penalty Additional Percentage Interest Rate Penalty Additional interest rate on notes per annum Additional Square Feet Leased Additional Square Feet Leased Additional office space leased (in square feet) Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature Reacquisition of conversion option in convertible notes Decrease to additional paid-in capital for repurchase of conversion option in convertible notes Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation Tax provision on stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock-based compensation Amount of increase in additional paid in capital (APIC) resulting from direct costs associated with issuing stock. Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Refund Refund of equity issuance costs Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs Equity component of convertible notes issuance cost Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Tax benefits realized from stock-based compensation Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile loss to net cash used in operating activities: Allowance for Doubtful Accounts [Member] Allowance for Doubtful Accounts Allowance for Estimated Chargebacks [Member] Allowance for Estimated Chargebacks [Member] Chargebacks Allowance for Sales Returns [Member] Allowance for Sales Returns Allowance for Trade Receivables [Member] Trade Receivables Amarin Pharmaceuticals Ireland Limited [Member] Amarin Pharmaceuticals Ireland Limited [Member] Amarin Pharmaceuticals Ireland Limited Amendment Flag Amendment Flag American Depositary Share American Depositary Share [Member] American Depositary Shares American Depository Shares [Member] American Depository Shares [Member] American Depositary Shares American Depository Shares to Shares Ratio American Depository Shares to Shares Ratio Number of shares that each ADS represents Amortization of Debt Issuance Costs and Discounts Amortization of debt discount and debt issuance costs Amortization of Intangible Assets Amortization of intangible asset Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Anti-dilutive securities Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Arrangements and Non-arrangement Transactions [Domain] Arrangements and Non-arrangement Transactions [Domain] As Adjusted [Member] As Adjusted [Member] Final As-Adjusted Assets TOTAL ASSETS Assets [Abstract] ASSETS Assets, Current Total current assets Total current assets Assets, Current [Abstract] Current Assets: Assets, Fair Value Disclosure [Abstract] Asset: Award Type [Axis] Award Type [Axis] Bedminster [Member] Bedminster [Member] Bedminster Beneficial Conversion Feature [Policy Text Block] Beneficial Conversion Feature [Policy Text Block] Beneficial Conversion Features Beneficial Ownership Limitation Percentage Beneficial Ownership Limitation Percentage Beneficial ownership limitation Biologix [Member] Biologix [Member] Biologix FZCo Biopharmaceutical [Member] Biopharmaceutical [Member] BioPharma Debt Bridge Loan [Member] Bridge Loan Business Development [Domain] Business Development [Domain] Business Development [Domain] Business Developments [Axis] Business Developments [Axis] Business Developments Cash and Cash Equivalents, at Carrying Value CASH AND CASH EQUIVALENTS, END OF PERIOD CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Cash equivalents-money markets Cash and Cash Equivalents, Period Increase (Decrease) NET DECREASE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents and Restricted Cash Cash Discount Invoice Terms Cash Discount Invoice Terms Sales discount term Cash Discount Percent Cash Discount Percent Sales discount percentage Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash items: Cash Paid During Period For [Abstract] Cash Paid During Period For [Abstract] Cash paid during the year for: Charges Cash [Member] Charges Cash [Member] Cash Class of Stock [Domain] Class of Stock [Domain] Class of Warrant or Right [Axis] Class of Warrant or Right Class Of Warrant Or Right Common Stock Exchange Ratio Class Of Warrant Or Right Common Stock Exchange Ratio Number of ADS that can be purchased for each warrant received Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Class of Warrant or Right, Exercised in Period Class of Warrant or Right, Exercised in Period Warrants exercised Class of Warrant or Right, Exercise Price of Warrants or Rights Exercise price of the warrants Class of Warrant or Right, Expired in Period Class of Warrant or Right, Expired in Period Warrants expired Class of Warrant or Right, Issued Class of Warrant or Right, Issued Number of warrants issued Class of Warrant or Right, Number of Securities Called by Each Warrant or Right Warrants issued, number of shares called by a warrant Class of Warrant or Right, Number of Securities Called by Warrants or Rights Warrants issued, number of shares called by the warrant Class of Warrant or Right, Outstanding Warrants outstanding Class of Warrant or Right, Term Class of Warrant or Right, Term Warrant term Clinical Trial Application Clinical Trial Application [Member] Clinical Trial Application Collaborative Arrangement Disclosure [Text Block] Development, Commercialization and Supply Agreements Commitments and Contingencies Commitments and contingencies (Note 9) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Line Items] Commitments and Contingencies Disclosure [Line Items] Commitments and Contingencies Disclosure [Line Items] Commitments and Contingencies Disclosure [Table] Commitments and Contingencies Disclosure [Table] Commitments and Contingencies Disclosure [Table] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Common Stock [Member] Common Shares Common Stock Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares, Issued Common stock, issued Common Stock, Shares, Outstanding Common stock, outstanding Common Stock, Value, Issued Common stock, £0.50 par value, unlimited authorized; 270,183,201 issued, 269,363,696 outstanding as of December 31, 2016; 183,577,765 issued, 183,403,263 outstanding as of December 31, 2015 Compensation and Employee Benefit Plans [Text Block] Defined Contribution Plan Compensation and Retirement Disclosure [Abstract] Compensation and Retirement Disclosure [Abstract] Computer Equipment and Capitalized Software [Member] Computer Equipment and Capitalized Software [Member] Computer equipment and software Computer Equipment [Member] Computer equipment Concentration Of Suppliers [Policy Text Block] Concentration Of Suppliers [Policy Text Block] Concentration of Suppliers Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk, Credit Risk, Policy [Policy Text Block] Concentration of Credit Risk Concentration Risk, Percentage Concentration risk percentage Concentration Risk Type [Domain] Concentration Risk Type [Domain] Condensed Financial Information of Subsidiaries Disclosure [Abstract] Condensed Financial Information of Subsidiaries Disclosure [Abstract] Condensed Financial Information of Subsidiaries Disclosure [Abstract] Consolidation, Policy [Policy Text Block] Principles of Consolidation Construction in Progress, Gross Construction in progress Conversion of Stock, Amount Converted Conversion of Series A Convertible Preferred Stock into common stock Conversion Price Per Share Conversion Price Per Share Share conversion price Convertible Debt Convertible notes, carrying amount net of unamortized discount Convertible Debt Carrying Value Exchanged Convertible Debt Carrying Value Exchanged Convertible senior notes, carrying value, exchanged Convertible Debt, Current Convertible senior notes, outstanding amount Convertible Debt [Member] Convertible Debt Convertible Preferred Stock, Shares Issued upon Conversion Number of shares issued for each preference shares Co Promotion Agreement Disclosure [Text Block] Co Promotion Agreement Disclosure [Text Block] Co-PromotionAgreement Co-Promotion Agreement [Line Items] Co-Promotion Agreement [Line Items] Co-Promotion Agreement [Line Items] Co Promotion Agreement [Member] Co Promotion Agreement [Member] Co-Promotion Agreement (the Agreement) Co-Promotion Agreement [Table] Co-Promotion Agreement [Table] Co-Promotion Agreement [Table] Cost of Goods Sold Less: Cost of goods sold Credits/payments Made for Prior Period Sales Credits/payments Made for Prior Period Sales Credits/payments made for prior period sales Current Federal Tax Expense (Benefit) Federal-U.S. Current Fiscal Year End Date Current Fiscal Year End Date Current Income Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Current State and Local Tax Expense (Benefit) State-U.S. Customer Concentration Risk [Member] Customer Concentration Risk Debt Conversion Description [Axis] Debt Conversion by Unique Description Debt Conversion, Name [Domain] Debt Conversion, Name [Domain] Debt Conversion, Original Debt, Amount Convertible senior notes, principal amount Exchange of exchangeable senior notes into common stock Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Line Items] Debt Disclosure [Line Items] Debt Disclosure [Line Items] Debt Disclosure [Table] Debt Disclosure [Table] Debt Disclosure [Table] Debt Disclosure [Text Block] Debt Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Convertible, Carrying Amount of Equity Component Carrying amount of debt conversion option Debt Instrument, Convertible, Conversion Price Bridge notes converted in conjunction with the private placement, price per share Convertible senior notes, initial exchange price Debt Instrument, Convertible, Conversion Ratio Convertible senior notes, exchange rate of ADS per $1,000 principal amount of notes Debt Instrument, Convertible, Number of Equity Instruments Convertible senior notes, total ADS into which the debt is exchangeable Debt Instrument, Convertible, Premium on Conversion Price, Percentage Debt Instrument, Convertible, Premium on Conversion Price, Percentage Convertible senior notes, percentage of premium initial exchange price Debt Instrument, Convertible, Threshold Consecutive Trading Days Convertible senior notes, mandatory exchange in whole or in part if daily VWAP equals or exceeds percentage of exchange price, at least number of VWAP Trading days Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Convertible senior notes, mandatory exchange in whole or in part if daily VWAP equals or exceeds percentage of exchange price Debt Instrument, Convertible, Threshold Trading Days Convertible senior notes, mandatory exchange in whole or in part if daily VWAP equals or exceeds percentage of exchange price, in any number of VWAP Trading days Debt Instrument, Date of First Required Payment Convertible senior notes, payment start date Debt Instrument, Face Amount Convertible senior notes, principal amount Debt Instrument, Fair Value Disclosure Convertible senior notes, fair value Exchangeable senior notes, estimated fair value Debt Instrument, Frequency of Periodic Payment Convertible senior notes, interest payable dates Debt Instrument, Increase, Accrued Interest Debt instrument increase accrued interest Debt Instrument, Interest Rate, Stated Percentage Convertible senior notes, stated interest rate Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument, Maturity Date Convertible senior notes, maturity date Debt Instrument Maturity Date Year Debt Instrument Maturity Date Year Convertible senior notes, due date Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Debt Instrument, Redemption Period, End Date Convertible senior notes redemption, end date Debt Instrument, Redemption Price, Percentage Convertible senior notes, repurchase price at option of the issuer Debt Instrument, Repurchased Face Amount Convertible senior notes, principal amount purchase Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument, Term Note, estimated remaining life Note, expected term Debt Instrument, Unamortized Discount Convertible senior notes, discount Debt Issuance Costs [Policy Text Block] Debt Issuance Costs [Policy Text Block] Debt Issuance Costs Debt, Policy [Policy Text Block] Debt Instruments Deferred Federal Income Tax Expense (Benefit) Federal-U.S. Debt Issuance Costs, Gross Offering costs Deferred Foreign Income Tax Expense (Benefit) Ireland and United Kingdom Deferred Income Tax Expense (Benefit) Deferred income taxes Total deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Deferred: Deferred Tax Liabilities, Gross Total deferred tax liabilities Deferred Revenue Deferred revenue Deferred Revenue Arrangement Type [Axis] Deferred Revenue Arrangement Type [Axis] Deferred Revenue [Domain] Deferred Revenue [Domain] Deferred Revenue, Current Deferred revenue, current Deferred Revenue, Noncurrent Deferred revenue, long-term Estimated number of days following the end of the quarter before related revenue is recognized. Deferred Revenue Recognition Period Revenue recognition period of non-refundable up-front payment Deferred State and Local Income Tax Expense (Benefit) State-U.S. Deferred Tax Assets, Depreciation and Amortization Deferred Tax Assets, Depreciation and Amortization Depreciation Deferred Tax Assets, Gross Gross deferred tax assets Deferred Tax Assets, Net Deferred tax assets Net deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Total deferred tax assets Deferred Tax Assets, Net [Abstract] Deferred tax assets: Deferred Tax Assets, Net of Valuation Allowance, Current Deferred tax assets, current Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Deferred tax assets Deferred tax assets, long-term Deferred Tax Assets, Operating Loss Carryforwards Net operating losses Deferred Tax Assets, Operating Loss Carryforwards, Change In Amount Deferred Tax Assets, Operating Loss Carryforwards, Change In Amount Decrease in net operating loss carryforwards from prior years Deferred Tax Assets, Operating Loss Carryforwards, Foreign Foreign net operating loss carryforwards Deferred Tax Assets, Tax Credit Carryforwards Tax credit carryforwards Tax credits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Stock based compensation Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves Other reserves and accrued liabilities Deferred Tax Assets, Valuation Allowance Ending valuation allowance Beginning valuation allowance Less: valuation allowance Deferred Tax Liabilities, Depreciation and Amortization Deferred Tax Liabilities, Depreciation and Amortization Depreciation Deferred Tax Liabilities, Net [Abstract] Deferred tax liabilities: Deferred Tax Liabilities, Subject to Expiration Deferred Tax Liabilities, Subject to Expiration Gross liabilities to expire in 2016 Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Contribution Plan, Employer Discretionary Contribution Amount Contributions made under defined contribution plan Depreciation Depreciation expense Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Derivative Contract [Domain] Derivative Contract [Domain] Derivative Liability, Fair Value, Gross Liability Derivative liability at fair value Derivative, Gain (Loss) on Derivative, Net Gain (loss) on change in fair value of derivatives