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Cash Discount Invoice Terms

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Cash Discount Percent

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Class of Warrant or Right, Exercised in Period

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Fair Value Assumptions Coupon Rate

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Maturity Period Used to Classify Investments

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Number of warrants or rights outstanding.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

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Fair value, before 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 elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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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, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability.

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Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

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Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

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Risk-free interest rate assumption used in valuing an instrument.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015 Segment	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2014
Significant Accounting Policies [Line Items]
Deferred revenue			$ 0us-gaap_DeferredRevenueCurrent	$ 1,700,000us-gaap_DeferredRevenueCurrent
Sales discount percentage		2.00%amrn_CashDiscountPercent
Sales discount term		30 days
Trade receivables, credit period	30 days
Accounts receivable written off	0amrn_WriteOffsOfAccountsReceivables
Warrants expiration date	Feb. 27, 2015
Warrants exercised	1,844,585
Warrant derivative liability			100,000us-gaap_DerivativeLiabilitiesCurrent
Derivative liability fair value assumptions, risk-free rate			0.04%
Derivative liability fair value assumptions, term			1 month 28 days
Derivative liability fair value assumptions, dividend yield			0.00%
Derivative liability fair value assumptions, volatility rate			79.00%
Increase (Decrease) in the fair value of warrant derivative liability	868,000
Gain (loss) on change in fair value of derivative liability	464,000us-gaap_UnrealizedGainLossOnDerivatives	4,393,000us-gaap_UnrealizedGainLossOnDerivatives
Long term debt redemption feature					14,600,000
Number of operating segments	1us-gaap_NumberOfOperatingSegments
Prior To Agreement
Significant Accounting Policies [Line Items]
Warrants expiration date	Oct. 16, 2014
Embedded Derivative Financial Instruments
Significant Accounting Policies [Line Items]
Gain (loss) on change in fair value of derivative liability	1,300,000	3,500,000
Change of control obligation					140,000,000
Maximum repayment of future revenue and receivables					150,000,000
Long term debt redemption feature	4,800,000		4,800,000
Gain (loss) on change in fair value of derivative liability	0
Preferred Stock Purchase Option
Significant Accounting Policies [Line Items]
Increase (Decrease) in the fair value of warrant derivative liability	868,000
Gain (loss) on change in fair value of derivative liability	(946,000)
Preferred stock purchase option derivative liability at fair value	900,000
Convertible Debt
Significant Accounting Policies [Line Items]
Carrying value include debt discount	3,500,000
Gain (loss) on change in fair value of derivative liability	1,300,000
Convertible Debt \| 2014 Notes
Significant Accounting Policies [Line Items]
Carrying value include debt discount	27,900,000					27,900,000
Derivative liability fair value assumptions, risk-free rate	2.50%		2.70%
Derivative liability fair value assumptions, dividend yield	20.60%		24.80%
Derivative liability fair value assumptions, volatility rate	82.00%		82.00%
Gain (loss) on change in fair value of derivative liability	1,300,000
Long term debt redemption feature	1,300,000		2,600,000
Convertible Debt \| 2012 Notes
Significant Accounting Policies [Line Items]
Carrying value include debt discount	0		0
Convertible Debt \| Non Cash \| 2014 Notes
Significant Accounting Policies [Line Items]
Carrying value include debt discount	26,800,000		28,200,000
Warrants Issued October 2009
Significant Accounting Policies [Line Items]
Warrants expiration date	Feb. 27, 2015
Warrants outstanding	0
Warrants exercised	1,844,585
Increase (Decrease) in the fair value of warrant derivative liability	100,000
Gain (loss) on change in fair value of derivative liability	$ 100,000
Warrants Issued October 2009 \| Prior To Agreement
Significant Accounting Policies [Line Items]
Warrants expiration date	Oct. 16, 2014
Top Three Customers \| Gross Product Sales \| Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	94.00%	96.00%
Top Three Customers \| Accounts Receivable \| Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk percentage	94.00%	95.00%
Minimum \| Embedded Derivative Financial Instruments
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term	2 years		2 years 3 months 18 days
Derivative liability fair value assumption, coupon rate	8.90%		9.80%
Derivative liability fair value assumptions, market yields	11.20%		10.00%
Maximum
Significant Accounting Policies [Line Items]
Short term highly liquid instruments, maturity date	90 days
Warrants outstanding			8,087,388
Maximum \| Embedded Derivative Financial Instruments
Significant Accounting Policies [Line Items]
Derivative liability fair value assumptions, term	5 years 10 months 24 days		3 years 7 months 6 days
Derivative liability fair value assumption, coupon rate	10.80%		10.80%
Derivative liability fair value assumptions, market yields	20.30%		16.80%
Maximum \| Warrants Issued October 2009
Significant Accounting Policies [Line Items]
Warrants outstanding			8,087,388