Recently Issued and Proposed Accounting Pronouncements (Details) $ in Millions	9 Months Ended
Sep. 30, 2015 USD ($)
The amendments ASU 2015-03 debt issuance costs
Reclassified debt issuance costs	$ 11.8

Represents the amount of debt issuance costs reclassified from long-term asset to reduction in carrying amount of debt.

No definition available.

Name:	amag_DebtIssuanceCostsReclassifiedToReductionInCarryingAmountOfDebt
Namespace Prefix:	amag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration