Equity	12 Months Ended
Dec. 31, 2015
Equity	(10) Equity Warrants During the year ended December 31, 2015, the Company issued 1,844,585 shares upon the exercise of warrants, resulting in gross and net proceeds of $2.8 million and $2.7 million, respectively. During the year ended December 31, 2014, the Company issued 1,684,888 shares upon the exercise of warrants, resulting in gross and net proceeds of $1.7 million. No warrants remained outstanding as of December 31, 2015. Incentive Equity Awards As of December 31, 2015, there were an aggregate of 17,818,053 stock options and 10,886,523 restricted stock units (“RSUs”) outstanding, representing approximately 7% and 4%, respectively, of outstanding shares (including common and preferred shares) on a fully diluted basis. During the years ended December 31, 2015 and 2014, the Company issued 18,020 and 234,500 shares, respectively, as a result of the exercise of stock options, resulting in gross and net proceeds of $31 thousand during the year ended December 31, 2015 and $0.3 million during the year ended December 31, 2014. On July 6, 2015, the Company granted a total of 1,455,000 RSUs and 5,470,000 stock options to employees under the Amarin Corporation plc Stock Incentive Plan (the “2011 Plan”). The RSUs granted vest over a four year period. Of the total stock options granted, 3,670,000 stock options vest over a four year period while the remaining 1,800,000 stock options vest upon the achievement of certain performance conditions. During the year ended December 31, 2015, the Company issued 181,876 common shares related to the vesting of these RSUs, of which 40,165 shares were retained as treasury shares as settlement of employee tax obligations. Also on July 6, 2015, the Company granted a total of 413,500 RSUs and 288,657 stock options to members of the Company’s Board of Directors under the 2011 Plan. Of the total awards granted, 283,500 RSUs and 121,506 stock options vest in equal installments over a three year period upon the earlier of the one-year anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year, while the remaining 130,000 RSUs and 167,151 stock options vest in full upon the earlier of the one-year anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year. Upon termination of service to the Company or upon a change of control, each Director shall be entitled to a payment equal to the fair market value of one share of Amarin common stock, which is required to be made in shares. On January 29, 2015, the Company granted a total of 2,564,251 RSUs and 1,622,500 stock options to employees under the 2011 Plan. The RSUs vest annually over a three year period and the stock options vest over a four year period. Also on January 29, 2015, the Company granted 5,455,500 RSUs to employees under the 2011 Plan that vest upon the achievement of certain performance conditions. The issuance of these performance RSUs was contingent upon shareholder approval to increase the aggregate number of shares authorized for issuance under the 2011 Plan, which was obtained at the Company’s Annual General Meeting of Shareholders held on July 6, 2015. On March 11, 2014, the Company granted a total of 173,348 RSUs and 205,890 stock options to members of the Company’s Board of Directors under the 2011 Plan. Upon termination of service to the Company or upon a change of control, each Director shall be entitled to a payment equal to the fair market value of one share of Amarin common stock, which is required to be made in shares. The RSUs vest in equal installments over a three year period upon the earlier of the anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year. The stock options vest in full upon the earlier of the anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year. On January 8, 2014, the Company granted a total of 2,082,000 RSUs and 2,605,500 stock options to employees under the 2011 Plan. The RSUs vest annually over a three year period and the stock options vest monthly over a four year period. During the year ended December 31, 2015, the Company issued 639,500 common shares related to the vesting of these RSUs, of which 114,258 shares were retained as treasury shares as settlement of employee tax obligations. See Note 12—Stock Incentive Plans and Stock Based Compensation for further information regarding the Company’s incentive equity awards. Tax Refund During the year ended December 31, 2014, the Company received a refund of $3.2 million for UK stamp duty taxes paid in prior periods related to the issuance of common stock. Such proceeds were recorded as an increase to additional paid-in capital. Preferred Stock On March 5, 2015, the Company entered into a subscription agreement with four institutional investors (the “Purchasers”), including both existing and new investors, for the private placement of 352,150,790 restricted American Depositary Shares, each representing one (1) share of Amarin’s Series A Convertible Preference Shares, par value £0.05 per share, in the capital of the Company (“Series A Preference Shares”), resulting in gross proceeds to the Company of $52.8 million. The closing of the private placement occurred on March 30, 2015. For each restricted American Depositary Share, the Purchasers paid a negotiated price of $0.15 (equating to $1.50 on an as-if-converted-to-ordinary-shares basis), resulting in $52.8 million in aggregate gross proceeds to the Company, before deducting estimated offering expenses of approximately $0.7 million. The net proceeds are reflected as preferred stock in the accompanying consolidated balance sheets. Each ten (10) Series A Preference Shares may be consolidated and redesignated as one (1) ordinary share, par value £0.50 per share, in the capital of the Company, each ordinary share to be represented by American Depositary Shares (“ADSs”), provided that consolidation will be prohibited if, as a result, the holder of such Series A Preference Shares and its affiliates would beneficially own more than 4.99% of the total number of Amarin ordinary shares or ADSs outstanding following such redesignation (the “Beneficial Ownership Limitation”). By written notice to the Company, a holder may from time to time increase or decrease the Beneficial Ownership Limitation to any other percentage not in excess of 19.9% specified in such notice; provided that any such increase will not be effective until the sixty-first (61st) day after such notice is delivered to the Company. This consolidation and redesignation may be effected by a holder of Series A Preference Shares following the first to occur of the resale of the ADSs representing the ordinary shares being registered for resale under the Securities Act pursuant to an effective registration statement, following any sale of the ADSs representing the ordinary shares pursuant to Rule 144 under the Securities Act, or if such ADSs representing the ordinary shares are eligible for sale under Rule 144, following the expiration of the one-year holding requirement under Rule 144. During the year ended December 31, 2015, at the request of the holders, a portion of the Series A Preference Shares were consolidated and redesignated, resulting in the issuance of 6,283,333 ADSs such that a maximum of 32,818,464 ordinary shares remain issuable upon future consolidation and redesignation of the remaining Series A Preference Shares, inclusive of the shares issued in July 2015 as discussed below, subject to certain adjustments for dilutive events. Except as otherwise provided in the Series A Preference Share Terms or as required by applicable law, the Series A Preference Shares have no voting rights. However, as long as any Series A Preference Shares are outstanding, the Company cannot, without the approval of the holders of seventy-five percent (75%) of the then outstanding Series A Preference Shares, alter or change adversely the powers, preferences or rights attaching to the Series A Preference Shares or enter into any agreement with respect to the foregoing. Holders of the Series A Preference Shares are entitled to receive, and the Company is required to pay, dividends (other than dividends in the form of ordinary shares) on the Series A Preference Shares equal (on an as-if-converted-to-ordinary-shares basis) to and in the same form as dividends (other than dividends in the form of ordinary shares) actually paid on ordinary shares when, as and if such dividends (other than dividends in the form of ordinary shares) are paid on the ordinary shares. The restricted American Depositary Shares and Series A Preference Shares have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), or state securities laws and may not be offered or sold in the United States absent registration with the Securities and Exchange Commission (SEC) or an applicable exemption from registration requirements. The Company filed a registration statement with the SEC covering the resale of the restricted American Depositary Shares and the ADSs representing ordinary shares created by the consolidation and redesignation of the Series A Preference Shares (the “Registrable Securities”) on April 9, 2015. In addition, the Company agreed to use its commercially reasonable best efforts to effect and to keep the registration, and any qualification, exemption or compliance under state securities laws which the Company determines to obtain, continuously effective, and to keep the Registration Statement free of any material misstatements or omissions, until the earlier of (a) March 11, 2017 or (b) the date on which all Registrable Securities held by Purchasers may be sold or transferred in compliance with Rule 144 under the Securities Act, without any volume or manner of sale restrictions. The Series A Preference Shares contain a contingent beneficial conversion feature (BCF) because they contain a conversion feature at a fixed rate that was in-the-money when issued. The BCF was recorded in the three months ended June 30, 2015 as a result of the related Form S-3 Registration Statement being declared effective, which represents the resolution of the contingency to convert the Series A Preference Shares. The BCF was recognized in stockholders’ deficit and was measured by allocating a portion of the proceeds equal to the intrinsic value of that feature to additional paid-in capital. The effective purchase price of the ordinary shares into which the preferred shares are convertible was $1.50, which was used to compute the intrinsic value. The intrinsic value was calculated as the difference between the effective purchase price of the ordinary shares and the market value ($2.39 per share) on the date the preferred shares were issued, multiplied by the number of shares into which the preferred shares are convertible. The BCF resulting from the issuance of the Series A Preference Shares was determined to be $31.3 million. The BCF was recorded as a non-cash dividend to preferred shareholders through accumulated deficit, and is therefore reflected as an adjustment to net loss applicable to common shareholders for earnings per common share purposes in accordance with GAAP. On March 30, 2015, in connection with the closing of the private placement, and pursuant to a pre-existing contractual right to participate in certain private placement transactions effected by the Company, the Company entered into a separate subscription agreement with an existing investor, Sofinnova Venture Partners VII L.P. (Sofinnova), for the purchase of an additional $5.8 million of restricted American Depositary Shares, each representing one (1) share of the Company’s Series A Preference Shares, at the same price per share and otherwise on substantially the same terms as the initial private placement (the “Second Private Placement”). In accordance with applicable marketplace rules of the NASDAQ Stock Market, the consummation of the Second Private Placement was conditioned upon approval by the Company’s shareholders at a future meeting of the Company’s shareholders. Such approval was received at the Company’s Annual General Meeting of Shareholders on July 6, 2015 and as a result, the closing of the Second Private Placement occurred on July 10, 2015. The Company issued 38,867,180 restricted ADSs, each representing one Series A Preference Share, which may be consolidated and redesignated from time to time up to a maximum of 3,886,718 ordinary shares, each ordinary share to be represented by one ADS. For each restricted ADS, Sofinnova paid a negotiated price of $0.15 (equating to $1.50 on an as-if-converted-to-ordinary-shares basis) resulting in gross proceeds to the Company of $5.8 million. Dr. James Healy, a member of the Company’s Board, is a managing member of Sofinnova Management VII, L.L.C. and a general partner of Sofinnova. The existence of this preferred stock purchase option was determined to be a derivative liability effective March 5, 2015, the date on which the private placement was initially subscribed. The fair value of this liability was calculated using a Black-Scholes model and was determined to be $0.9 million at inception and was charged to accumulated deficit as a deemed non-cash dividend to Sofinnova. The liability was then marked to fair value as of March 30, 2015, the date on which the Company executed a subscription agreement with Sofinnova, resulting in a charge of $0.9 million through (loss) gain on change in fair value of derivatives. The liability of $1.8 million was reclassified to permanent equity (additional paid-in capital) on such date. Subsequent to approval of the Second Private Placement, the Company recorded the remaining value of the BCF related to this share issuance as a non-cash dividend to preferred shareholders through accumulated deficit. The value of the BCF was determined on the same basis as the first private placement and amounted to $3.4 million less $1.8 million previously recorded for the preferred stock purchase option for a net non-cash charge of $1.6 million.

(10) Equity

Warrants

During the year ended December 31, 2015, the Company issued 1,844,585 shares upon the exercise of warrants, resulting in gross and net proceeds of $2.8 million and $2.7 million, respectively. During the year ended December 31, 2014, the Company issued 1,684,888 shares upon the exercise of warrants, resulting in gross and net proceeds of $1.7 million. No warrants remained outstanding as of December 31, 2015.

Incentive Equity Awards

As of December 31, 2015, there were an aggregate of 17,818,053 stock options and 10,886,523 restricted stock units (“RSUs”) outstanding, representing approximately 7% and 4%, respectively, of outstanding shares (including common and preferred shares) on a fully diluted basis.

During the years ended December 31, 2015 and 2014, the Company issued 18,020 and 234,500 shares, respectively, as a result of the exercise of stock options, resulting in gross and net proceeds of $31 thousand during the year ended December 31, 2015 and $0.3 million during the year ended December 31, 2014.

On July 6, 2015, the Company granted a total of 1,455,000 RSUs and 5,470,000 stock options to employees under the Amarin Corporation plc Stock Incentive Plan (the “2011 Plan”). The RSUs granted vest over a four year period. Of the total stock options granted, 3,670,000 stock options vest over a four year period while the remaining 1,800,000 stock options vest upon the achievement of certain performance conditions. During the year ended December 31, 2015, the Company issued 181,876 common shares related to the vesting of these RSUs, of which 40,165 shares were retained as treasury shares as settlement of employee tax obligations.

Also on July 6, 2015, the Company granted a total of 413,500 RSUs and 288,657 stock options to members of the Company’s Board of Directors under the 2011 Plan. Of the total awards granted, 283,500 RSUs and 121,506 stock options vest in equal installments over a three year period upon the earlier of the one-year anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year, while the remaining 130,000 RSUs and 167,151 stock options vest in full upon the earlier of the one-year anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year. Upon termination of service to the Company or upon a change of control, each Director shall be entitled to a payment equal to the fair market value of one share of Amarin common stock, which is required to be made in shares.

On January 29, 2015, the Company granted a total of 2,564,251 RSUs and 1,622,500 stock options to employees under the 2011 Plan. The RSUs vest annually over a three year period and the stock options vest over a four year period. Also on January 29, 2015, the Company granted 5,455,500 RSUs to employees under the 2011 Plan that vest upon the achievement of certain performance conditions. The issuance of these performance RSUs was contingent upon shareholder approval to increase the aggregate number of shares authorized for issuance under the 2011 Plan, which was obtained at the Company’s Annual General Meeting of Shareholders held on July 6, 2015.

On March 11, 2014, the Company granted a total of 173,348 RSUs and 205,890 stock options to members of the Company’s Board of Directors under the 2011 Plan. Upon termination of service to the Company or upon a change of control, each Director shall be entitled to a payment equal to the fair market value of one share of Amarin common stock, which is required to be made in shares. The RSUs vest in equal installments over a three year period upon the earlier of the anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year. The stock options vest in full upon the earlier of the anniversary of the grant date or the Company’s annual general meeting of shareholders in such anniversary year.

On January 8, 2014, the Company granted a total of 2,082,000 RSUs and 2,605,500 stock options to employees under the 2011 Plan. The RSUs vest annually over a three year period and the stock options vest monthly over a four year period. During the year ended December 31, 2015, the Company issued 639,500 common shares related to the vesting of these RSUs, of which 114,258 shares were retained as treasury shares as settlement of employee tax obligations.

See Note 12—Stock Incentive Plans and Stock Based Compensation for further information regarding the Company’s incentive equity awards.

Tax Refund

During the year ended December 31, 2014, the Company received a refund of $3.2 million for UK stamp duty taxes paid in prior periods related to the issuance of common stock. Such proceeds were recorded as an increase to additional paid-in capital.

Preferred Stock

On March 5, 2015, the Company entered into a subscription agreement with four institutional investors (the “Purchasers”), including both existing and new investors, for the private placement of 352,150,790 restricted American Depositary Shares, each representing one (1) share of Amarin’s Series A Convertible Preference Shares, par value £0.05 per share, in the capital of the Company (“Series A Preference Shares”), resulting in gross proceeds to the Company of $52.8 million. The closing of the private placement occurred on March 30, 2015.

For each restricted American Depositary Share, the Purchasers paid a negotiated price of $0.15 (equating to $1.50 on an as-if-converted-to-ordinary-shares basis), resulting in $52.8 million in aggregate gross proceeds to the Company, before deducting estimated offering expenses of approximately $0.7 million. The net proceeds are reflected as preferred stock in the accompanying consolidated balance sheets.

Each ten (10) Series A Preference Shares may be consolidated and redesignated as one (1) ordinary share, par value £0.50 per share, in the capital of the Company, each ordinary share to be represented by American Depositary Shares (“ADSs”), provided that consolidation will be prohibited if, as a result, the holder of such Series A Preference Shares and its affiliates would beneficially own more than 4.99% of the total number of Amarin ordinary shares or ADSs outstanding following such redesignation (the “Beneficial Ownership Limitation”). By written notice to the Company, a holder may from time to time increase or decrease the Beneficial Ownership Limitation to any other percentage not in excess of 19.9% specified in such notice; provided that any such increase will not be effective until the sixty-first (61st) day after such notice is delivered to the Company. This consolidation and redesignation may be effected by a holder of Series A Preference Shares following the first to occur of the resale of the ADSs representing the ordinary shares being registered for resale under the Securities Act pursuant to an effective registration statement, following any sale of the ADSs representing the ordinary shares pursuant to Rule 144 under the Securities Act, or if such ADSs representing the ordinary shares are eligible for sale under Rule 144, following the expiration of the one-year holding requirement under Rule 144. During the year ended December 31, 2015, at the request of the holders, a portion of the Series A Preference Shares were consolidated and redesignated, resulting in the issuance of 6,283,333 ADSs such that a maximum of 32,818,464 ordinary shares remain issuable upon future consolidation and redesignation of the remaining Series A Preference Shares, inclusive of the shares issued in July 2015 as discussed below, subject to certain adjustments for dilutive events.

Except as otherwise provided in the Series A Preference Share Terms or as required by applicable law, the Series A Preference Shares have no voting rights. However, as long as any Series A Preference Shares are outstanding, the Company cannot, without the approval of the holders of seventy-five percent (75%) of the then outstanding Series A Preference Shares, alter or change adversely the powers, preferences or rights attaching to the Series A Preference Shares or enter into any agreement with respect to the foregoing.

Holders of the Series A Preference Shares are entitled to receive, and the Company is required to pay, dividends (other than dividends in the form of ordinary shares) on the Series A Preference Shares equal (on an as-if-converted-to-ordinary-shares basis) to and in the same form as dividends (other than dividends in the form of ordinary shares) actually paid on ordinary shares when, as and if such dividends (other than dividends in the form of ordinary shares) are paid on the ordinary shares.

The restricted American Depositary Shares and Series A Preference Shares have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), or state securities laws and may not be offered or sold in the United States absent registration with the Securities and Exchange Commission (SEC) or an applicable exemption from registration requirements. The Company filed a registration statement with the SEC covering the resale of the restricted American Depositary Shares and the ADSs representing ordinary shares created by the consolidation and redesignation of the Series A Preference Shares (the “Registrable Securities”) on April 9, 2015. In addition, the Company agreed to use its commercially reasonable best efforts to effect and to keep the registration, and any qualification, exemption or compliance under state securities laws which the Company determines to obtain, continuously effective, and to keep the Registration Statement free of any material misstatements or omissions, until the earlier of (a) March 11, 2017 or (b) the date on which all Registrable Securities held by Purchasers may be sold or transferred in compliance with Rule 144 under the Securities Act, without any volume or manner of sale restrictions.

The Series A Preference Shares contain a contingent beneficial conversion feature (BCF) because they contain a conversion feature at a fixed rate that was in-the-money when issued. The BCF was recorded in the three months ended June 30, 2015 as a result of the related Form S-3 Registration Statement being declared effective, which represents the resolution of the contingency to convert the Series A Preference Shares. The BCF was recognized in stockholders’ deficit and was measured by allocating a portion of the proceeds equal to the intrinsic value of that feature to additional paid-in capital. The effective purchase price of the ordinary shares into which the preferred shares are convertible was $1.50, which was used to compute the intrinsic value. The intrinsic value was calculated as the difference between the effective purchase price of the ordinary shares and the market value ($2.39 per share) on the date the preferred shares were issued, multiplied by the number of shares into which the preferred shares are convertible. The BCF resulting from the issuance of the Series A Preference Shares was determined to be $31.3 million. The BCF was recorded as a non-cash dividend to preferred shareholders through accumulated deficit, and is therefore reflected as an adjustment to net loss applicable to common shareholders for earnings per common share purposes in accordance with GAAP.

On March 30, 2015, in connection with the closing of the private placement, and pursuant to a pre-existing contractual right to participate in certain private placement transactions effected by the Company, the Company entered into a separate subscription agreement with an existing investor, Sofinnova Venture Partners VII L.P. (Sofinnova), for the purchase of an additional $5.8 million of restricted American Depositary Shares, each representing one (1) share of the Company’s Series A Preference Shares, at the same price per share and otherwise on substantially the same terms as the initial private placement (the “Second Private Placement”). In accordance with applicable marketplace rules of the NASDAQ Stock Market, the consummation of the Second Private Placement was conditioned upon approval by the Company’s shareholders at a future meeting of the Company’s shareholders. Such approval was received at the Company’s Annual General Meeting of Shareholders on July 6, 2015 and as a result, the closing of the Second Private Placement occurred on July 10, 2015. The Company issued 38,867,180 restricted ADSs, each representing one Series A Preference Share, which may be consolidated and redesignated from time to time up to a maximum of 3,886,718 ordinary shares, each ordinary share to be represented by one ADS. For each restricted ADS, Sofinnova paid a negotiated price of $0.15 (equating to $1.50 on an as-if-converted-to-ordinary-shares basis) resulting in gross proceeds to the Company of $5.8 million. Dr. James Healy, a member of the Company’s Board, is a managing member of Sofinnova Management VII, L.L.C. and a general partner of Sofinnova.

The existence of this preferred stock purchase option was determined to be a derivative liability effective March 5, 2015, the date on which the private placement was initially subscribed. The fair value of this liability was calculated using a Black-Scholes model and was determined to be $0.9 million at inception and was charged to accumulated deficit as a deemed non-cash dividend to Sofinnova. The liability was then marked to fair value as of March 30, 2015, the date on which the Company executed a subscription agreement with Sofinnova, resulting in a charge of $0.9 million through (loss) gain on change in fair value of derivatives. The liability of $1.8 million was reclassified to permanent equity (additional paid-in capital) on such date. Subsequent to approval of the Second Private Placement, the Company recorded the remaining value of the BCF related to this share issuance as a non-cash dividend to preferred shareholders through accumulated deficit. The value of the BCF was determined on the same basis as the first private placement and amounted to $3.4 million less $1.8 million previously recorded for the preferred stock purchase option for a net non-cash charge of $1.6 million.