Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Feb. 12, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	AMAG PHARMACEUTICALS INC.
Entity Central Index Key	0000792977
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,125,000
Entity Common Stock, Shares Outstanding		34,748,689
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY