Represents the milestone payments received or receivable under the agreement.

No definition available.

Name:	amag_CollaborativeArrangementMilestonePaymentsReceived
Namespace Prefix:	amag_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the potential milestone payments expected to be received by the entity under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	amag_CollaborativeArrangementsPotentialMilestonePaymentsExpectedToBeReceived
Namespace Prefix:	amag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The number of years over which the amount of previously reported deferred or unearned revenue is recognized as revenue.

+ References

No definition available.

+ Details

Name:	amag_RecognitionOfDeferredRevenueAmortizationPeriod
Namespace Prefix:	amag_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

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.

+ 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.4(a).Q1)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

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

- Definition

Amount of previously reported deferred or unearned revenue that was recognized as revenue during the period. Deferred revenue is a liability 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

+ Details

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

- Definition

Cash received from collaborators during the current period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=amag_LicenseDevelopmentAndCommercializationAgreementWithTakedaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Collaborative Agreements (Details) (USD $)	1 Months Ended		3 Months Ended	12 Months Ended
Collaborative Agreements (Details) (USD $)	Apr. 30, 2010	Mar. 31, 2010	Mar. 31, 2015	Dec. 31, 2012	Dec. 31, 2014
Collaborative Agreements
Deferred revenues, short-term			$ 33,563,000us-gaap_DeferredRevenueCurrent		$ 44,376,000us-gaap_DeferredRevenueCurrent
License Development and Commercialization Agreement with Takeda [Member]
Collaborative Agreements
Upfront payment received	61,000,000
Period of recognition of deferred revenues		10 years	9 months
Milestone revenue				18,000,000
Deferred revenue recognized in earnings related to the amortization of the deferred revenue balance			12,000,000
Deferred revenues, short-term			33,600,000
License Development and Commercialization Agreement with Takeda [Member] \| Termination Agreement [Member]
Collaborative Agreements
Milestone payments expected to be received under the agreement			3,000,000
License Development and Commercialization Agreement with Takeda [Member] \| Termination Agreement [Member] \| Maximum
Collaborative Agreements
Milestone revenue			$ 6,700,000