Estimated number of days following the end of the quarter before related revenue is recognized.

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Eligible milestone payment.

+ References

No definition available.

+ Details

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Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Eligible regulatory milestone event payment.

+ References

No definition available.

+ Details

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Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Eligible sales based milestone event payment.

+ References

No definition available.

+ Details

Name:	amrn_EligibleSalesBasedMilestoneEventPayment
Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

License And Collaboration Agreements [Line Items]

+ References

No definition available.

+ Details

Name:	amrn_LicenseAndCollaborationAgreementsLineItems
Namespace Prefix:	amrn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Licensing agreement term.

+ References

No definition available.

+ Details

Name:	amrn_LicensingAgreementTerm
Namespace Prefix:	amrn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Non refundable upfront payments received.

+ References

No definition available.

+ Details

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Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Non refundable upfront payments received period.

+ References

No definition available.

+ Details

Name:	amrn_NonRefundableUpfrontPaymentsReceivedPeriod
Namespace Prefix:	amrn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Nonrefundable milestone payment.

+ References

No definition available.

+ Details

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Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of regulatory milestone events indications.

+ References

No definition available.

+ Details

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Namespace Prefix:	amrn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

+ Details

Name:	us-gaap_DeferredRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Revenue earned during the period relating to consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_LicensesRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	amrn_BusinessDevelopmentsAxis=amrn_EddingpharmMember
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=amrn_ClinicalTrialApplicationMember
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Balance Type:
Period Type:

- Details

Name:	amrn_BusinessDevelopmentsAxis=amrn_BiologixMember
Namespace Prefix:
Data Type:	na
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- Details

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Development, Commercialization and Supply Agreement - Additional Information (Detail)	1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Mar. 31, 2016 USD ($)	Feb. 28, 2015 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Item	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
License And Collaboration Agreements [Line Items]
Licensing revenue				$ 309,000	$ 293,000	$ 895,000	$ 825,000
Deferred revenue	$ 19,200,000			$ 19,200,000		$ 19,200,000		$ 15,100,000
Eddingpharm
License And Collaboration Agreements [Line Items]
Non-refundable up-front received			$ 15,000,000
Licensing agreement term			16 years
Number of indications of the regulatory milestone events relating to the submission and approval \| Item						3
Amounts to be received upon achievement of the regulatory milestone events						$ 33,000,000
Sales-based milestone event payment						120,000,000
Eddingpharm \| Maximum
License And Collaboration Agreements [Line Items]
Additional upfront payment eligible to receive based on development, regulatory and sales Milestone						153,000,000
Amounts to be received upon achievement of the regulatory milestone events						15,000,000
Sales-based milestone event payment						50,000,000
Eddingpharm \| Minimum
License And Collaboration Agreements [Line Items]
Amounts to be received upon achievement of the regulatory milestone events						1,000,000
Sales-based milestone event payment						5,000,000
Eddingpharm \| Clinical Trial Application
License And Collaboration Agreements [Line Items]
Licensing agreement term		4 years
Non-refundable milestone payment		$ 1,000,000
Biologix FZCo
License And Collaboration Agreements [Line Items]
Revenue recognition period of non-refundable up-front payment		10 years
HLS
License And Collaboration Agreements [Line Items]
Non-refundable up-front received	$ 5,000,000
Licensing agreement term	12 years 6 months
Non-refundable up-front received period	6 months
HLS \| Maximum
License And Collaboration Agreements [Line Items]
Additional upfront payment eligible to receive based on development, regulatory and sales Milestone						$ 60,000,000