<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.7.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>214</ContextCount>
  <ElementCount>263</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>66</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Condensed Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperations</Role>
      <ShortName>Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Condensed Consolidated Statement of Changes in Stockholders' Deficit</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/StatementCondensedConsolidatedStatementOfChangesInStockholdersDeficit</Role>
      <ShortName>Condensed Consolidated Statement of Changes in Stockholders' Deficit</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Disclosure - Nature of Business and Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureNatureOfBusinessAndBasisOfPresentation</Role>
      <ShortName>Nature of Business and Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Disclosure - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPolicies</Role>
      <ShortName>Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - Inventory</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureInventory</Role>
      <ShortName>Inventory</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureEquity</Role>
      <ShortName>Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Co-Promotion Agreement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureCoPromotionAgreement</Role>
      <ShortName>Co-Promotion Agreement</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Development, Commercialization and Supply Agreements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDevelopmentCommercializationAndSupplyAgreements</Role>
      <ShortName>Development, Commercialization and Supply Agreements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPolicies</ParentRole>
      <Position>17</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPoliciesTables</Role>
      <ShortName>Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPolicies</ParentRole>
      <Position>18</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssets</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Inventory (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureInventoryTables</Role>
      <ShortName>Inventory (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureInventory</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Nature of Business and Basis of Presentation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureNatureOfBusinessAndBasisOfPresentationAdditionalInformationDetail</Role>
      <ShortName>Nature of Business and Basis of Presentation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Summarize Activity of the Net Product Revenue Allowance and Reserve Categories (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSummarizeActivityOfNetProductRevenueAllowanceAndReserveCategoriesDetail</Role>
      <ShortName>Summarize Activity of the Net Product Revenue Allowance and Reserve Categories (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Summarizes the Impact of Accounts Receivable Reserves on Gross Trade Accounts Receivable (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureSummarizesImpactOfAccountsReceivableReservesOnGrossTradeAccountsReceivableDetail</Role>
      <ShortName>Summarizes the Impact of Accounts Receivable Reserves on Gross Trade Accounts Receivable (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Estimated Useful Lives (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureEstimatedUsefulLivesDetail</Role>
      <ShortName>Estimated Useful Lives (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Net Loss and the Number of Shares Used to Compute Basic and Diluted Loss per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureNetLossAndNumberOfSharesUsedToComputeBasicAndDilutedLossPerShareDetail</Role>
      <ShortName>Net Loss and the Number of Shares Used to Compute Basic and Diluted Loss per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Anti-Dilutive Securities Not Included in the Computation of Net Loss per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureAntiDilutiveSecuritiesNotIncludedInComputationOfNetLossPerShareDetail</Role>
      <ShortName>Anti-Dilutive Securities Not Included in the Computation of Net Loss per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Assets and Liability Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureAssetsAndLiabilityMeasuredAtFairValueOnRecurringBasisDetail</Role>
      <ShortName>Assets and Liability Measured at Fair Value on Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Carrying Amounts and Estimated Fair Values of Debt Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureCarryingAmountsAndEstimatedFairValuesOfDebtInstrumentsDetail</Role>
      <ShortName>Carrying Amounts and Estimated Fair Values of Debt Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssetsAdditionalInformationDetail</Role>
      <ShortName>Intangible Assets - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssetsDetail</Role>
      <ShortName>Intangible Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureIntangibleAssetsTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Inventory (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureInventoryDetail</Role>
      <ShortName>Inventory (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureInventoryTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Debt - Long-Term Debt from Royalty-Bearing Instrument-December 2012 Financing - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDebtLongTermDebtFromRoyaltyBearingInstrumentDecember2012FinancingAdditionalInformationDetail</Role>
      <ShortName>Debt - Long-Term Debt from Royalty-Bearing Instrument-December 2012 Financing - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Debt - January 2012, May 2014, and November 2015 Exchangeable Senior Notes - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDebtJanuary2012May2014AndNovember2015ExchangeableSeniorNotesAdditionalInformationDetail</Role>
      <ShortName>Debt - January 2012, May 2014, and November 2015 Exchangeable Senior Notes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Debt - January 2017 Exchangeable Senior Notes - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDebtJanuary2017ExchangeableSeniorNotesAdditionalInformationDetail</Role>
      <ShortName>Debt - January 2017 Exchangeable Senior Notes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Equity - Preferred Stock - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureEquityPreferredStockAdditionalInformationDetail</Role>
      <ShortName>Equity - Preferred Stock - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Equity - Incentive Equity Awards - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureEquityIncentiveEquityAwardsAdditionalInformationDetail</Role>
      <ShortName>Equity - Incentive Equity Awards - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Co-Promotion Agreement - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureCoPromotionAgreementAdditionalInformationDetail</Role>
      <ShortName>Co-Promotion Agreement - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="amrn-20170630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Development, Commercialization and Supply Agreement - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.amarincorp.com/20170630/taxonomy/role/DisclosureDevelopmentCommercializationAndSupplyAgreementAdditionalInformationDetail</Role>
      <ShortName>Development, Commercialization and Supply Agreement - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>amrn-20170630.xml</File>
    <File>amrn-20170630.xsd</File>
    <File>amrn-20170630_cal.xml</File>
    <File>amrn-20170630_def.xml</File>
    <File>amrn-20170630_lab.xml</File>
    <File>amrn-20170630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
