The approximate percentage of revenues from customers outside the U.S. to total revenues.

No definition available.

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3044-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13537-108611

+ Details

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- Definition

Sum of investments and unrestricted cash as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1,2)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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- Definition

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_MajorCustomersAxis=amag_CaremarkMember
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- Details

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- Details

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- Details

Name:	us-gaap_MajorCustomersAxis=amag_TakedaPharmaceuticalCompanyLimitedMember
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- Details

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- Details

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Basis of Presentation and Summary of Significant Accounting Policies - Concentrations and Significant Customer Information (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2014
Concentrations and Significant Customer Information
Cash, cash equivalents and investments	$ 546,500		$ 546,500		$ 546,500
Investment in institutional money market funds	19,000		19,000		19,000
Cash and cash equivalents	$ 251,110	$ 228,705	$ 251,110	$ 89,884	$ 251,110	$ 89,884	$ 119,296
Sales Revenue, Net \| Minimum
Concentrations and Significant Customer Information
Concentration risk (as a percent)			10.00%	10.00%	10.00%	10.00%
Sales Revenue, Net \| Customer Concentration Risk \| Amerisource Bergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk (as a percent)			22.00%	19.00%	23.00%	24.00%
Sales Revenue, Net \| Customer Concentration Risk \| Caremark LLC (Specialty Pharmacy)
Concentrations and Significant Customer Information
Concentration risk (as a percent)			10.00%		10.00%
Sales Revenue, Net \| Customer Concentration Risk \| Caremark LLC (Specialty Pharmacy) \| Maximum
Concentrations and Significant Customer Information
Concentration risk (as a percent)				10.00%		10.00%
Sales Revenue, Net \| Customer Concentration Risk \| McKesson Corporation
Concentrations and Significant Customer Information
Concentration risk (as a percent)						10.00%
Sales Revenue, Net \| Customer Concentration Risk \| McKesson Corporation \| Maximum
Concentrations and Significant Customer Information
Concentration risk (as a percent)			10.00%	10.00%	10.00%
Sales Revenue, Net \| Customer Concentration Risk \| Takeda Pharmaceutical Company Limited
Concentrations and Significant Customer Information
Concentration risk (as a percent)				32.00%		24.00%
Sales Revenue, Net \| Geographic Concentration Risk
Concentrations and Significant Customer Information
Approximate percentage of revenues from customers outside the U.S.						24.00%
Accounts Receivable \| Maximum
Concentrations and Significant Customer Information
Concentration risk (as a percent)			10.00%	10.00%	10.00%	10.00%
Accounts Receivable \| Credit Concentration Risk \| Amerisource Bergen Drug Corporation
Concentrations and Significant Customer Information
Concentration risk (as a percent)	13.00%	43.00%
Accounts Receivable \| Credit Concentration Risk \| Caremark LLC (Specialty Pharmacy)
Concentrations and Significant Customer Information
Concentration risk (as a percent)	11.00%
Accounts Receivable \| Credit Concentration Risk \| Caremark LLC (Specialty Pharmacy) \| Maximum
Concentrations and Significant Customer Information
Concentration risk (as a percent)		10.00%