Debt	12 Months Ended
Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	(7) Debt Long-Term Debt from Royalty-Bearing Instrument—December 2012 Financing On December 6, 2012, the Company entered into a Purchase and Sale Agreement with BioPharma Secured Debt Fund II Holdings Cayman LP, or BioPharma. Under this agreement, the Company granted to BioPharma a security interest in future receivables associated with the Vascepa patent rights, in exchange for $100.0 million received at the closing of the agreement which occurred in December 2012. Under these terms, the Company continues to own all Vascepa intellectual property rights, however, such rights, as described below, could be used as collateral for repayment of the remaining unpaid balance under this agreement if the Company defaults on making required payments. In the agreement, the Company agreed to repay BioPharma up to $150.0 million with such repayment based on a portion of net revenues and receivables generated from Vascepa. On December 20, 2017, BioPharma assigned all rights under this agreement to CPPIB Credit Europe S.à r.l., or CPPIB. As of December 31, 2019, the remaining amount to be repaid to CPPIB is $52.4 million. During the year ended December 31, 2019, the Company made repayments under the agreement of $36.2 million to CPPIB and an additional $14.2 million was paid in February 2020 for the fourth quarter of 2019. These payments, as well as additional quarterly repayments scheduled in the future, are calculated as 10% of Vascepa net revenues. All such payments reduce the remainder of the $150.0 million in aggregate payments to CPPIB. Except upon a change of control in Amarin, the agreement does not expire until $150.0 million in aggregate has been repaid. The Company can prepay the net remaining amount at any time. The Company determined the redemption feature upon a change of control to be an embedded derivative requiring bifurcation. The fair value of the embedded derivative was calculated by determining the fair value of the debt with the change in control provision included and also without the change in control provision. The fair value of this derivative liability is remeasured at each reporting period, with changes in fair value recognized in the consolidated statement of operations and any changes in the assumptions used in measuring the fair value of the derivative liability could result in a material increase or decrease in its carrying value. Based on current assumptions underlying the valuation, the Company recognized no gain or loss on change in fair value of derivative liability during the years ended December 31, 2019 and 2018. As of December 31, 2019 and 2018, the carrying value of the royalty-bearing instrument, net of the unamortized debt discount and issuance costs, was $49.7 million and $79.7 million, respectively. During the year ended December 31, 2019, the Company recorded cash and non-cash interest expense of $4.4 million and $1.6 million, respectively, in connection with the royalty-bearing instrument. During the year ended December 31, 2018, the Company recorded $5.6 million and $2.0 million of cash and non-cash interest expense, respectively, in connection with the royalty-bearing instrument. The Company will periodically evaluate the remaining term of the agreement and the effective interest rate is recalculated each period based on the Company’s most current estimate of repayment. To secure the obligations under the agreement, the Company granted BioPharma, which it subsequently assigned to CPPIB, a security interest in the Company’s patents, trademarks, trade names, domain names, copyrights, know-how and regulatory approvals related to the covered products, all books and records relating to the foregoing and all proceeds of the foregoing, referred to collectively as the collateral. If the Company (i) fails to deliver a payment when due and does not remedy that failure within a specific notice period, (ii) fails to maintain a first-priority perfected security interest in the collateral in the United States and does not remedy that failure after receiving notice of such failure or (iii) becomes subject to an event of bankruptcy, then CPPIB may attempt to collect the maximum amount payable by the Company under this agreement (after deducting any payments the Company has already made). Under the agreement, the Company is restricted from paying dividends on its common shares, unless it has cash and cash equivalents in excess of a specified amount after such payment. January 2017 Exchangeable Senior Notes On January 20, 2017, the Company and Corsicanto II DAC, or Corsicanto II, a designated activity company formed under the laws of Ireland and a wholly owned subsidiary of the Company, entered into separate, privately negotiated purchase agreements with certain investors pursuant to which Corsicanto II issued and sold $30.0 million in aggregate principal amount of 3.5% exchangeable senior notes due 2047, or the 2017 Notes, at an issue price of 100%. In October 2018, Corsicanto II mandatorily exchanged $30.0 million of aggregate principal amount of the 2017 Notes for equity, such that no 2017 Notes remained outstanding as of December 31, 2019 and 2018.

Debt

12 Months Ended

Dec. 31, 2019

(7) Debt

Long-Term Debt from Royalty-Bearing Instrument—December 2012 Financing

On December 6, 2012, the Company entered into a Purchase and Sale Agreement with BioPharma Secured Debt Fund II Holdings Cayman LP, or BioPharma. Under this agreement, the Company granted to BioPharma a security interest in future receivables associated with the Vascepa patent rights, in exchange for $100.0 million received at the closing of the agreement which occurred in December 2012. Under these terms, the Company continues to own all Vascepa intellectual property rights, however, such rights, as described below, could be used as collateral for repayment of the remaining unpaid balance under this agreement if the Company defaults on making required payments. In the agreement, the Company agreed to repay BioPharma up to $150.0 million with such repayment based on a portion of net revenues and receivables generated from Vascepa. On December 20, 2017, BioPharma assigned all rights under this agreement to CPPIB Credit Europe S.à r.l., or CPPIB.

As of December 31, 2019, the remaining amount to be repaid to CPPIB is $52.4 million. During the year ended December 31, 2019, the Company made repayments under the agreement of $36.2 million to CPPIB and an additional $14.2 million was paid in February 2020 for the fourth quarter of 2019. These payments, as well as additional quarterly repayments scheduled in the future, are calculated as 10% of Vascepa net revenues. All such payments reduce the remainder of the $150.0 million in aggregate payments to CPPIB. Except upon a change of control in Amarin, the agreement does not expire until $150.0 million in aggregate has been repaid. The Company can prepay the net remaining amount at any time.

The Company determined the redemption feature upon a change of control to be an embedded derivative requiring bifurcation. The fair value of the embedded derivative was calculated by determining the fair value of the debt with the change in control provision included and also without the change in control provision. The fair value of this derivative liability is remeasured at each reporting period, with changes in fair value recognized in the consolidated statement of operations and any changes in the assumptions used in measuring the fair value of the derivative liability could result in a material increase or decrease in its carrying value. Based on current assumptions underlying the valuation, the Company recognized no gain or loss on change in fair value of derivative liability during the years ended December 31, 2019 and 2018.

As of December 31, 2019 and 2018, the carrying value of the royalty-bearing instrument, net of the unamortized debt discount and issuance costs, was $49.7 million and $79.7 million, respectively. During the year ended December 31, 2019, the Company recorded cash and non-cash interest expense of $4.4 million and $1.6 million, respectively, in connection with the royalty-bearing instrument. During the year ended December 31, 2018, the Company recorded $5.6 million and $2.0 million of cash and non-cash interest expense, respectively, in connection with the royalty-bearing instrument. The Company will periodically evaluate the remaining term of the agreement and the effective interest rate is recalculated each period based on the Company’s most current estimate of repayment.

To secure the obligations under the agreement, the Company granted BioPharma, which it subsequently assigned to CPPIB, a security interest in the Company’s patents, trademarks, trade names, domain names, copyrights, know-how and regulatory approvals related to the covered products, all books and records relating to the foregoing and all proceeds of the foregoing, referred to collectively as the collateral. If the Company (i) fails to deliver a payment when due and does not remedy that failure within a specific notice period, (ii) fails to maintain a first-priority perfected security interest in the collateral in the United States and does not remedy that failure after receiving notice of such failure or (iii) becomes subject to an event of bankruptcy, then CPPIB may attempt to collect the maximum amount payable by the Company under this agreement (after deducting any payments the Company has already made).

Under the agreement, the Company is restricted from paying dividends on its common shares, unless it has cash and cash equivalents in excess of a specified amount after such payment.

January 2017 Exchangeable Senior Notes

On January 20, 2017, the Company and Corsicanto II DAC, or Corsicanto II, a designated activity company formed under the laws of Ireland and a wholly owned subsidiary of the Company, entered into separate, privately negotiated purchase agreements with certain investors pursuant to which Corsicanto II issued and sold $30.0 million in aggregate principal amount of 3.5% exchangeable senior notes due 2047, or the 2017 Notes, at an issue price of 100%. In October 2018, Corsicanto II mandatorily exchanged $30.0 million of aggregate principal amount of the 2017 Notes for equity, such that no 2017 Notes remained outstanding as of December 31, 2019 and 2018.