XML 65 R51.htm IDEA: XBRL DOCUMENT
v3.20.4

Equity - Common Stock - Additional Information (Detail) $ / shares in Units, $ in Thousands, £ in Millions | Dec. 13, 2019 GBP (£) shares | Jul. 29, 2019 USD ($) | Jul. 18, 2019 $ / shares shares | Nov. 29, 2018 USD ($) $ / shares shares | Mar. 05, 2018 shares | Feb. 01, 2018 USD ($) $ / shares shares | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 13, 2019 $ / shares
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Stockholders Equity Note [Line Items] |  |  |  |  |  |  |  |  |
Accrued expenses and other current liabilities | $ |  |  |  |  |  |  | $ 198,641 | $ 139,826 |
American Depositary Shares |  |  |  |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |  |  |  |
Issuance of stock (shares) | shares |  |  | 22,222,223 |  |  | 19,178,082 |  |  |
Sale of stock price per share | $ / shares |  |  | $ 18.00 |  |  |  |  |  |
Commissions, price per share | $ / shares |  |  | $ 17.235 |  |  | $ 3.41 |  |  |
Over allotment option, exercisable period |  |  | 30 days |  |  | 30 days |  |  |
American Depositary Shares | Over-Allotment Option |  |  |  |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |  |  |  |
Issuance of stock (shares) | shares |  |  |  | 11,111,112 |  |  |  |  |
Commissions, price per share | $ / shares |  |  |  | $ 17.575 |  |  |  |  |
Issuance of stock (shares), exercised | shares |  |  | 3,333,333 |  | 1,438,356 | 2,876,712 |  |  |
Gross proceeds from public offering including exercised option | $ |  | $ 460,000 |  |  |  |  |  |  |
Net proceeds from public offering including exercised option | $ |  | $ 440,100 |  | $ 194,800 |  | $ 70,000 |  |  |
Food and Drug Administration |  |  |  |  |  |  |  |  |
Stockholders Equity Note [Line Items] |  |  |  |  |  |  |  |  |
Milestone payment achieved | £ | £ 5 |  |  |  |  |  |  |  |
Issuance of common stock for milestone payment (in shares) | shares | 257,713 |  |  |  |  |  |  |  |
Shares issued, price per share | $ / shares |  |  |  |  |  |  |  |  | $ 24.12
Accrued expenses and other current liabilities | $ |  |  |  |  |  |  |  | $ 2,200 |

X
- Definition Accrued liabilities and other liabilities current. + References No definition available. + Details
Name: | amrn_AccruedLiabilitiesAndOtherLiabilitiesCurrent
Namespace Prefix: | amrn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Commissions, price per share. + References No definition available. + Details
Name: | amrn_CommissionsPricePerShare
Namespace Prefix: | amrn_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Milestone payment received. + References No definition available. + Details
Name: | amrn_MilestonePaymentReceived
Namespace Prefix: | amrn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proceeds from issuance of common stock including stock option exercises. + References No definition available. + Details
Name: | amrn_ProceedsFromIssuanceOfCommonStockIncludingStockOptionExercises
Namespace Prefix: | amrn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Proceeds from issuance of common stock including stock option exercises net. + References No definition available. + Details
Name: | amrn_ProceedsFromIssuanceOfCommonStockIncludingStockOptionExercisesNet
Namespace Prefix: | amrn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public offering over allotment option exercise period. + References No definition available. + Details
Name: | amrn_PublicOfferingOverAllotmentOptionExercisePeriod
Namespace Prefix: | amrn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stock issued during period, shares, milestone payment. + References No definition available. + Details
Name: | amrn_StockIssuedDuringPeriodSharesMilestonePayment
Namespace Prefix: | amrn_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stock issued during period shares new issues exercised. + References No definition available. + Details
Name: | amrn_StockIssuedDuringPeriodSharesNewIssuesExercised
Namespace Prefix: | amrn_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stockholders Equity Note [Line Items] + References No definition available. + Details
Name: | amrn_StockholdersEquityNoteLineItems
Namespace Prefix: | amrn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=amrn_AmericanDepositaryShareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=amrn_FoodAndDrugAdministrationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |