Assumed Sales Revenue for Royalty Payments

No definition available.

Name:	amrn_AssumedSalesRevenueForRoyaltyPayments
Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	amrn_CommitmentsAndContingenciesDisclosureLineItems
Namespace Prefix:	amrn_
Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Commitments To Purchase Or Fund Investments

+ References

No definition available.

+ Details

Name:	amrn_CommitmentsToPurchaseOrFundInvestments
Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Development Fees Committed

+ References

No definition available.

+ Details

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

- Definition

Number of Agreements

+ References

No definition available.

+ Details

Name:	amrn_NumberOfAgreements
Namespace Prefix:	amrn_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Potential Milestone Payments

+ References

No definition available.

+ Details

Name:	amrn_PotentialMilestonePayments
Namespace Prefix:	amrn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Potential Royalty Payment as Percentage of Net Sales

+ References

No definition available.

+ Details

Name:	amrn_PotentialRoyaltyPaymentAsPercentageOfNetSales
Namespace Prefix:	amrn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

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

- Definition

The aggregate carrying amount, as of the balance sheet date, of liabilities not separately disclosed in the balance sheet.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.15)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, beyond the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the long-term.

+ References

No definition available.

+ Details

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

- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

+ Details

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

- Definition

The amount the entity has committed to make for future royalty guarantees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 928

-SubTopic 440

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6473578&loc=d3e63223-108013

+ Details

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

Commitments and Contingencies - Additional Information (Detail)	6 Months Ended					1 Months Ended		1 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 30, 2012 Amr One Hundred One USD ($) Contract	Jun. 30, 2012 Amr One Hundred One Maximum USD ($)	Jun. 30, 2012 Amr One Hundred One Maximum Initial Payment USD ($)	Jun. 30, 2012 Fourth API supplier Maximum USD ($)	Jul. 31, 2011 Chemport USD ($)	Jun. 30, 2012 Chemport USD ($)	May 31, 2012 Chemport Commitments USD ($)	Jul. 31, 2011 Chemport Commitments USD ($)	Jun. 30, 2012 Chemport Commitments USD ($)	Dec. 31, 2009 Elan USD ($)	Jun. 30, 2012 Up On First Marketing Approval of AMR101 USD ($)	Jun. 30, 2012 Net sales up to GBP100 million ($162.0 million at December 31, 2010) Laxdale Limited	Jun. 30, 2012 Net sales up to GBP100 million ($162.0 million at December 31, 2010) Laxdale Limited Maximum USD ($)	Jun. 30, 2012 Net sales up to GBP100 million ($162.0 million at December 31, 2010) Laxdale Limited Maximum GBP (£)	Jun. 30, 2012 Net sales between GBP100 million ($162.0 million) and GBP500 million ($810.0 million) Laxdale Limited	Jun. 30, 2012 Net sales between GBP100 million ($162.0 million) and GBP500 million ($810.0 million) Laxdale Limited Maximum USD ($)	Jun. 30, 2012 Net sales between GBP100 million ($162.0 million) and GBP500 million ($810.0 million) Laxdale Limited Maximum GBP (£)	Jun. 30, 2012 Net sales between GBP100 million ($162.0 million) and GBP500 million ($810.0 million) Laxdale Limited Minimum USD ($)	Jun. 30, 2012 Net sales between GBP100 million ($162.0 million) and GBP500 million ($810.0 million) Laxdale Limited Minimum GBP (£)	Jun. 30, 2012 Net sales in excess of GBP500 million Laxdale Limited	Jun. 30, 2012 Net sales in excess of GBP500 million Laxdale Limited Minimum USD ($)	Jun. 30, 2012 Net sales in excess of GBP500 million Laxdale Limited Minimum GBP (£)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Potential Marketing Approval 1 USD ($)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Potential Marketing Approval 1 GBP (£)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Potential Marketing Approval 2 USD ($)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Potential Marketing Approval 2 GBP (£)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Maximum USD ($)	Jun. 30, 2012 First Indication for AMR101 Laxdale Limited Maximum GBP (£)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Potential Marketing Approval 1 USD ($)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Potential Marketing Approval 1 GBP (£)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Potential Marketing Approval 2 USD ($)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Potential Marketing Approval 2 GBP (£)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Maximum USD ($)	Jun. 30, 2012 Further Indication for AMR101 Laxdale Limited Maximum GBP (£)
Commitments and Contingencies Disclosure [Line Items]
One-time non-refundable payment due to the supplier												$ 500,000
Minimum purchase obligations	35,300,000
Number of signed agreements		2
Development fees committed			500,000		2,300,000
Raw material purchase commitment		1,100,000		5,000,000	15,000,000
Minority share equity investment commitment							3,300,000			400,000
Cash paid for cost method investment	825,000					1,700,000		800,000	400,000
Potential milestone payments											200,000
Potential royalty payment as a percentage of net sales													1.00%			0.50%					0.25%
Net sales for potential royalty payments														156,000,000	100,000,000		780,700,000	500,000,000	156,000,000	100,000,000		780,700,000	500,000,000
Potential aggregate stock or cash payment																								$ 11,700,000	£ 7,500,000	$ 11,700,000	£ 7,500,000	$ 23,400,000	£ 15,000,000	$ 7,800,000	£ 5,000,000	$ 7,800,000	£ 5,000,000	$ 15,600,000	£ 10,000,000