Recently Issued and Proposed Accounting Pronouncements (Details)	6 Months Ended
Jun. 30, 2012 item
Recently Issued and Proposed Accounting Pronouncements
Number of continuous statements presented by the entity to reflect the components of other comprehensive income and of net income	1
Number of separate statements in which the entity is required to present comprehensive income	2

Represents the number of continuous statements presented by the entity to reflect the net income, components of other comprehensive income.

No definition available.

Name:	amag_NewAccountingPronouncementOrChangeInAccountingPrincipleNumberOfContinuousStatements
Namespace Prefix:	amag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration