DESCRIPTION OF BUSINESS	12 Months Ended
DESCRIPTION OF BUSINESS	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	DESCRIPTION OF BUSINESS AMAG Pharmaceuticals, Inc., a Delaware corporation, was founded in 1981. We are a pharmaceutical company focused on bringing innovative products to patients with unmet medical needs by leveraging our development and commercial expertise to invest in and grow our pharmaceutical products across a range of therapeutic areas. Our currently marketed products support the health of patients in the areas of hematology and maternal and women’s health, including Feraheme^®(ferumoxytol injection) for intravenous use, Makena^®(hydroxyprogesterone caproate injection) auto-injector, Intrarosa^®(prasterone) vaginal inserts and Vyleesi^®(bremelanotide injection). In addition to our marketed products, our portfolio includes two product candidates, AMAG-423 (digoxin immune fab (ovine)), which is being studied for the treatment of severe preeclampsia, and ciraparantag, which is being studied as an anticoagulant reversal agent. In March 2019, we announced topline results from the Progestin’s Role in Optimizing Neonatal Gestation clinical trial (“PROLONG” or “Trial 003”), a randomized, double-blinded, placebo-controlled clinical trial evaluating Makena in patients with a history of a prior spontaneous singleton preterm delivery. The PROLONG trial was conducted under the U.S. Food and Drug Administration’s (the “FDA”) “Subpart H” accelerated approval process. The approval of Makena was based primarily on the Meis trial (“Trial 002”), which was conducted by the Maternal-Fetal Medicine Units Network, sponsored by the National Institute of Child Health and Human Development. In contrast to the Meis trial, the PROLONG trial did not demonstrate a statistically significant difference between the treatment and placebo arms for the co-primary endpoints. On October 29, 2019, the Advisory Committee met to discuss the results of the PROLONG trial to inform the FDA’s regulatory decision for Makena. Following various presentations by experts and discussions at the meeting, the FDA’s Bone, Reproductive and Urologic Drugs Advisory Committee (the “Advisory Committee”) voted as follows: (a) in response to the question “Do the findings from Trial 003 verify the clinical benefits of Makena on neonatal outcomes?”, 16 members voted “No” and no members voted “Yes”; (b) in response to the question “Based on the findings from Trial 002 and Trial 003, is there substantial evidence of effectiveness of Makena in reducing the risk of recurrent preterm birth?”, 13 members voted “No” and three members voted “Yes”; and (c) in response to the question, “Should the FDA (A) pursue withdrawal of approval for Makena, (B) leave Makena on the market under accelerated approval and require a new confirmatory trial, or (C) leave Makena on the market without requiring a new confirmatory trial?”, nine members voted for (A), seven members voted for (B) and no members voted for (C). The FDA is not required to follow the recommendations of its Advisory Committees, but will take them into consideration in deciding what regulatory steps to take with respect to Makena. We are unable to predict the outcome or timing of any FDA action with respect to Makena. In December 2019 we completed a review of our product portfolio and strategy. This strategic review resulted in our intention to divest Intrarosa^® (prasterone) and Vyleesi^® (bremelanotide), as announced in January 2020. We determined that these anticipated actions did not result in the related assets meeting the criteria to be recorded as held of sale at December 31, 2019. We are subject to risks common to companies in the pharmaceutical industry including, but not limited to (as such risks pertain to our business) the impact of any action by the FDA with respect to Makena, including the potential of the removal of Makena’s approval, our ability to successfully divest Intrarosa and Vyleesi, our ability to successfully commercialize our products, intense competition, including from generic products; maintaining and defending the proprietary nature of our technology, including in the event that Sandoz launches a generic version of Feraheme in accordance with the 2018 settlement agreement; our dependence upon third-party manufacturers and our potential inability to obtain raw or other materials and impacts of supply shortages; our reliance on and the extent of reimbursement from third parties for the use of our products, including the impact of generic competitors, Makena’s high Medicaid reimbursement concentration; our ability to expand our product portfolio through business development transactions; the approval of our product candidates and our ability to commercialize such products, if approved; potential litigation, including securities and product liability suits; our ability to work effectively and collaboratively with our licensors and partners; our reliance on other third parties in our business, including to conduct our clinical trials and undertake our product and distribution; our ability to maintain, attract and retain key employees; our potential failure to comply with federal and state healthcare fraud and abuse laws, marketing disclosure laws, or other federal and state laws and regulations and potential civil or criminal penalties as a result thereof; uncertainties regarding reporting and payment obligations under government pricing programs; post-approval commitments for Feraheme; our ability to comply with data protection laws and regulations; the impact of disruptions to our information technology systems; our level of and ability to repay our indebtedness; our access to sufficient capital; the availability of net operating loss carryforwards and other tax assets; potential differences between actual future results and the estimates or assumptions used by us in preparation of our consolidated financial statements, including goodwill and intangible assets; the volatility of our stock price; the potential fluctuation of our operating results; and provisions in our charter, by-laws and certain contracts that discourage an acquisition of our company. Throughout this Annual Report on Form 10-K, AMAG Pharmaceuticals, Inc. and our consolidated subsidiaries are collectively referred to as “the Company,” “AMAG,” “we,” “us,” or “our.”