Abingworth LLP [Member] Abingworth LLP [Member] Abingworth LLP Accounting Policies [Abstract] Accounting Policies [Abstract] 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 Net receivable Accounts Receivable, Net, Current Accounts receivable, net Accounts receivable, net Accrued Expenses And Other Liabilities Current Accrued Expenses And Other Liabilities Current Accrued expenses and other current liabilities Accrued expenses and other current liabilities 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 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 to Additional Paid in Capital, Other Reacquisition of conversion option in convertible notes Decrease to additional paid-in capital,representing reacquisition of conversion option in convertible notes Adjustments To Additional Paid In Capital, Resulting From Conversion Of Convertible Debt Into Equity Adjustments To Additional Paid In Capital, Resulting From Conversion Of Convertible Debt Into Equity Conversion option contained in exchangeable notes 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, 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: Agreement [Axis] Agreement [Axis] Agreement [Axis] Agreement [Domain] Agreement [Domain] Agreement [Domain] Allowance for Sales Returns [Member] Allowance for Sales Returns Allowance for Trade Receivables [Member] Allowance for Trade Receivables Allowances for Estimated Chargebacks Allowances for Estimated Chargebacks Chargebacks Allowances for Prompt Pay Discounts and DSA Allowances for Prompt Pay Discounts and DSA Trade allowances 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 Share American Depository Shares [Member] American Depository Shares [Member] American Depository Shares American Depository Shares to Shares Ratio American Depository Shares to Shares Ratio Number of shares that each ADS represents Amortization of Debt Discount (Premium) Interest expense, amortization of discount Amortization of Financing Costs and Discounts Amortization of debt discount and debt issuance costs Amortization of Intangible Assets Amortization of intangible asset Amount Of Potential Future Financial Obligations Amount Of Potential Future Financial Obligations Potential payment over the agreement terms Amr One Hundred One [Member] Amr One Hundred One [Member] Amr One Hundred One Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Anti-dilutive securities Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Assets TOTAL ASSETS Assets [Abstract] ASSETS Assets, Current 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 Biopharmaceutical [Member] Biopharmaceutical [Member] Biopharma Debt Bridge Loan [Member] Bridge Loan Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Axis] Business Acquisition Business Development [Domain] Business Development [Domain] Business Development [Domain] Business Developments [Axis] Business Developments [Axis] Business Developments Capitalized Computer Software, Gross Software 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) INCREASE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Cash Discount Invoice Terms Cash Discount Invoice Terms Sales discount term Cash Discount Percent Cash Discount Percent Sales discount percentage Cash Paid During Period For [Abstract] Cash Paid During Period For [Abstract] Cash paid during the year for: Change In Control Obligations Change In Control Obligations Change of control obligation Charges Cash [Member] Charges Cash [Member] Cash Chemport [Member] Chemport [Member] Chemport Class of Stock [Domain] Class of Stock [Domain] Class Of Warrant Expiration Date Class Of Warrant Expiration Date Warrants expiration date 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 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 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 Commitments [Member] Anticipated investment before the end of 2012 Commitments To Purchase Or Fund Investments Commitments To Purchase Or Fund Investments Minority share equity investment commitment Common Stock [Member] Common Shares 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; 174,610,451 issued, 174,590,372 outstanding at December 31, 2014; 172,691,063 issued, 172,670,984 outstanding at December 31, 2013 Compensation and Employee Benefit Plans [Text Block] Defined Contribution Plan Compensation and Retirement Disclosure [Abstract] Compensation and Retirement Disclosure [Abstract] Component Of Operating Cost And Expense [Line Items] Component Of Operating Cost And Expense [Line Items] Component Of Operating Cost And Expense [Line Items] Component Of Operating Cost And Expense [Table] Component Of Operating Cost And Expense [Table] Component Of Operating Cost And Expense [Table] Computer Equipment and Capitalized Software [Member] Computer Equipment and Capitalized Software [Member] Computer equipment and software Computer equipment, Gross Computer equipment, Gross Computer equipment 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] Concentrations Of Suppliers Policy [Text Block] Concentrations Of Suppliers Policy [Text Block] Concentration of Suppliers 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 Convertible Debt Carrying value of 2014 notes Convertible Debt, Fair Value Disclosures Record initial fair value of derivative liability on 2014 senior notes Convertible Debt [Member] Convertible Debt Co Promotion Agreement Disclosure [Text Block] Co Promotion Agreement Disclosure [Text Block] Co-Promotion Agreement Co-Promotion Agreement [Line Items] Co-Promotion Agreement [Line Items] Co-Promotion Agreement [Line Items] Co-Promotion Agreement [Table] Co-Promotion Agreement [Table] Co-Promotion Agreement [Table] Cost of Goods Sold Cost of goods sold expensed 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, Converted Instrument, Shares Issued Convertible senior notes, total ADS into which the debt is exchangeable Debt Conversion, Name [Domain] Debt Conversion, Name [Domain] Debt Conversion, Original Debt, Amount Bridge notes converted in conjunction with the private placement, amount 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 Exchange [Member] Debt Exchange [Member] Exchanged Debt Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Call Date, Earliest Convertible senior notes, earliest redemption date 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, Remaining Discount Amortization Period Debt discount amortization period 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, 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 Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument, Term Note, estimated remaining life Debt Instrument, Unamortized Discount Carrying value include debt discount Convertible senior notes, discount Debt Issuance Cost Underwriter's fees and offering costs 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. 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 Revenue, Additions Deferred product revenue Deferred Revenue, Current Deferred revenue 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 asset Deferred Tax Assets, Net of Valuation Allowance Deferred Tax Assets, Net of Valuation Allowance, Total Deferred Tax Assets, Net [Abstract] Deferred tax assets: Deferred Tax Assets, Net of Valuation Allowance, Current Deferred tax assets Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Deferred tax assets 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, Subject to Expiration Deferred Tax Liabilities, Subject to Expiration Gross liabilities to expire in 2015 Defined Benefit Plan, Contributions by Employer Contributions made under defined contribution plan Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Depreciation Depreciation expense Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Derivative Amount Outstanding Derivative Amount Outstanding Derivative, amount outstanding Derivative, by Nature [Axis] Derivative, by Nature Derivative Contract [Domain] Derivative Contract [Domain] Derivative Liability, Fair Value, Gross Liability Derivative liability, fair value Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Warrants and Warrant Derivative Liability Derivative Liability Ending Balance Beginning Balance Derivative liability Derivative Liability, Current Warrant derivative liability Derivative Liability, Noncurrent Long-term debt derivative liabilities Derivative Liabilities Transferred to Stockholders' Equity Derivative Liabilities Transferred to Stockholders' Equity Transfers to equity Derivative [Line Items] Derivative [Line Items] Derivative, Name [Domain] Derivative, Name [Domain] Derivatives, Embedded Derivatives [Policy Text Block] Long Term Debt Derivative Liabilities Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Derivatives, Policy [Policy Text Block] Derivative Instruments Derivative [Table] Derivative [Table]