Summarizes Activity of the Net Product Revenue Allowance and Reserve Categories (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 2,469
Provision related to current period and deferred sales	32,460	11,646
Provision related to prior period sales	(128)amrn_ProvisionRelatedToPriorPeriodSales
Credits/payments made for current period and deferred sales	(25,431)	(9,177)
Credits/payments made for prior period sales	(2,280)
Ending balance	7,090	2,469
Allowance for Trade Receivables
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	1,071
Provision related to current period and deferred sales	8,157	4,178
Provision related to prior period sales	(29)
Credits/payments made for current period and deferred sales	(5,950)	(3,107)
Credits/payments made for prior period sales	(1,042)
Ending balance	2,207	1,071
Rebates Chargebacks And Discounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	1,137
Provision related to current period and deferred sales	12,753	4,282
Provision related to prior period sales	(80)
Credits/payments made for current period and deferred sales	(9,143)	(3,145)
Credits/payments made for prior period sales	(1,057)
Ending balance	3,610	1,137
Allowance for Sales Returns
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	72
Provision related to current period and deferred sales	397	72
Provision related to prior period sales	12
Ending balance	481	72
Other Incentive Programs
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	189
Provision related to current period and deferred sales	11,153	3,114
Provision related to prior period sales	(31)
Credits/payments made for current period and deferred sales	(10,338)	(2,925)
Credits/payments made for prior period sales	(181)
Ending balance	$ 792	$ 189

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- Definition

Provision Related to Prior Period Sales

+ References

No definition available.

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- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

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Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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