Derivative Liabilities Transferred to Stockholders' Equity

No definition available.

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

- Definition

Share-based compensation net.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Convertible Security

-URI http://asc.fasb.org/extlink&oid=6509036

+ Details

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

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13495-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

+ Details

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

- 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_DerivativesFairValueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase (decrease) during the period in the carrying value of derivative instruments reported as liabilities that are due to be disposed of within one year (or the normal operating cycle, if longer).

+ References

No definition available.

+ Details

Name:	us-gaap_IncreaseDecreaseInDerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

+ Details

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

- Details

Name:	us-gaap_DerivativeByNatureAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=amrn_WarrantsIssuedOctoberTwentyZeroNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EmbeddedDerivativeFinancialInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=amrn_PreferredStockPurchaseOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Change in Fair Value of Derivative Liabilities (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivatives, Fair Value [Line Items]
Beginning Balance				$ 7,519	$ 17,994
Record derivative liability				868
Record initial fair value of derivative liability on 2014 senior notes			$ 3,500		3,500
(Gain) loss on change in fair value of derivative liabilities		$ 230	(4,466)	366	(11,870)
Transfer derivative liability to equity				(1,814)
Ending Balance	$ 6,930	6,930	9,121	6,930	9,121
Warrant
Derivatives, Fair Value [Line Items]
Compensation income for change in fair value of warrants issued to former employees				(9)	(503)
Warrants Issued October 2009
Derivatives, Fair Value [Line Items]
Beginning Balance				119	6,894
(Gain) loss on change in fair value of derivative liabilities				(110)	(6,270)
Ending Balance			121		121
Warrants Issued October 2009 \| Warrant
Derivatives, Fair Value [Line Items]
Compensation income for change in fair value of warrants issued to former employees				(9)	(503)
Embedded Derivative Financial Instruments
Derivatives, Fair Value [Line Items]
Beginning Balance				7,400	11,100
Record initial fair value of derivative liability on 2014 senior notes			3,500		3,500
(Gain) loss on change in fair value of derivative liabilities	300			(470)	(5,600)
Ending Balance	$ 6,930	$ 6,930	$ 9,000	6,930	$ 9,000
Preferred Stock Purchase Option
Derivatives, Fair Value [Line Items]
Record derivative liability				868
(Gain) loss on change in fair value of derivative liabilities				946
Transfer derivative liability to equity				$ (1,814)