v3.19.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2019
May 03, 2019
Document and Entity Information    
Entity Registrant Name AMAG PHARMACEUTICALS INC.  
Entity Central Index Key 0000792977  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Document Type 10-Q  
Document Period End Date Mar. 31, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Current Reporting Status Yes  
Entity Common Stock, Shares Outstanding (in shares)   33,766,939