XML 40 R30.htm IDEA: XBRL DOCUMENT
v3.21.2

Intangible Asset - Additional Information (Detail) £ in Millions, $ in Millions | 1 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2021 USD ($) | Jun. 30, 2021 | Mar. 31, 2021 GBP (£)
Finite-Lived Intangible Assets [Line Items] |  |  |
Intangible asset estimated weighted- average remaining life |  | 9 years 9 months 18 days |
Food and Drug Administration |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Milestone payment achieved | £ |  |  | £ 7.5
Increase in intangible assets | $ | $ 12.0 |  |

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

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 926 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) during the reporting period in intangible assets (for example patents and licenses). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
Name: | us-gaap_IncreaseDecreaseInIntangibleAssetsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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