Represents minimum amount of fees required to pay in the event a definitive agreement for an acquisition transaction is entered prior to April 2013

No definition available.

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

Commitments and Contingencies (Details) (Contractual Obligations, USD $) In Millions, unless otherwise specified	1 Months Ended	6 Months Ended
	Oct. 31, 2011	Jun. 30, 2012	Jun. 30, 2011
Contractual Obligations
Commitment and Contingencies
Allos Merger Agreement termination fees			$ 12.0
Expense reimbursement amount paid in connection with Merger Agreement Termination	2.0
Jefferies Agreement potential minimum termination fees		$ 1.5