XML 50 R40.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Equity - Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands |  |  | 9 Months Ended
--- | --- | --- | ---
Mar. 05, 2018 | Feb. 01, 2018 | Sep. 30, 2018
Stockholders Equity Note [Line Items] |  |  |
Net proceeds from public offering |  |  | $ 70,007
American Depositary Shares |  |  |
Stockholders Equity Note [Line Items] |  |  |
Issuance of stock (shares) |  | 19,178,082 |
Over allotment option, exercisable period |  | 30 days |
Sale of stock price per share |  | $ 3.41 |
Net proceeds from public offering |  | $ 70,000 |
American Depositary Shares | Over-Allotment Option |  |  |
Stockholders Equity Note [Line Items] |  |  |
Issuance of stock (shares) |  | 2,876,712 |
Issuance of stock (shares), exercised | 1,438,356 |  |

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 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 The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 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=6877327&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=27012166&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=6877327&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: |