Amag Pharmaceuticals (AMAG) 10-Q 5 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 29, 2014
Document and Entity Information	'	'
Entity Registrant Name	'AMAG PHARMACEUTICALS INC.	'
Entity Central Index Key	'0000792977	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	21,915,093
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$200,916	$26,986
Investments	184,557	186,803
Accounts receivable, net	10,115	6,842
Inventories	20,804	17,217
Receivable from collaboration	202	278
Prepaid and other current assets	4,410	3,396
Restricted cash	'	2,883
Total current assets	421,004	244,405
Property and equipment, net	1,837	1,846
Intangible assets, net	16,815	16,844
Restricted cash	400	400
Other long-term assets	6,407	1,964
Total assets	446,463	265,459
Current liabilities:	'	'
Accounts payable	5,125	2,629
Accrued expenses	21,851	22,266
Deferred revenues	9,118	8,226
Total current liabilities	36,094	33,121
Long-term liabilities:	'	'
Convertible 2.5% senior notes, net	162,561	'
Deferred revenues	40,567	44,534
Acquisition-related contingent consideration	14,040	13,609
Other long-term liabilities	2,105	1,787
Total liabilities	255,367	93,051
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred stock, par value $0.01 per share, 2,000,000 shares authorized; none issued	'	'
Common stock, par value $0.01 per share, 58,750,000 shares authorized; 21,877,192 and 21,772,571 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	219	218
Additional paid-in capital	667,653	641,941
Accumulated other comprehensive loss	-3,414	-3,491
Accumulated deficit	-473,362	-466,260
Total stockholders' equity	191,096	172,408
Total liabilities and stockholders' equity	$446,463	$265,459

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED BALANCE SHEETS	'	'
Convertible senior notes, interest rate (as a percent)	2.50%	'
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	58,750,000	58,750,000
Common stock, shares issued	21,877,192	21,772,571
Common stock, shares outstanding	21,877,192	21,772,571

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues:	'	'
U.S. Feraheme product sales, net	$17,375	$15,578
License fee and other collaboration revenues	3,120	2,003
Other product sales and royalties	340	299
Total revenues	20,835	17,880
Costs and expenses:	'	'
Cost of product sales	2,837	2,942
Research and development expenses	6,498	5,404
Selling, general and administrative expenses	17,491	14,005
Total costs and expenses	26,826	22,351
Other income (expense):	'	'
Interest expense	-1,476	'
Interest and dividend income, net	265	271
Gains on sale of assets	100	299
Gains on investments, net	'	6
Total other income (expense)	-1,111	576
Net loss	($7,102)	($3,895)
Net loss per share:	'	'
Basic and diluted (in dollars per share)	($0.33)	($0.18)
Weighted average shares outstanding used to compute net loss per share:	'	'
Basic and diluted (in shares)	21,824	21,544

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS	'	'
Net loss	($7,102)	($3,895)
Unrealized gains (losses) on securities:	'	'
Holding gains (losses) arising during period, net of tax	77	-87
Reclassification adjustment for (gains) losses included in net loss	'	-6
Net unrealized gains (losses) on securities	77	-93
Total comprehensive loss	($7,025)	($3,988)

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net loss	($7,102)	($3,895)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	162	650
Amortization of premium/discount on purchased securities	664	681
Write-down of inventory to net realizable value	1,437	'
Non-cash equity-based compensation expense	1,930	2,283
Amortization of debt discount and debt issuance costs	851	'
Gains on sale of assets	-100	-299
Gains on investments, net	'	-6
Change in fair value of contingent consideration	789	'
Changes in operating assets and liabilities:	'	'
Accounts receivable, net	-3,273	-2,109
Inventories	-2,521	1,834
Receivable from collaboration	76	155
Prepaid and other current assets	-1,014	-6
Other long-term assets	885	'
Accounts payable and accrued expenses	-1,101	-7,074
Deferred revenues	-3,075	-1,816
Other long-term liabilities	318	-111
Total adjustments	-3,972	-5,818
Net cash used in operating activities	-11,074	-9,713
Cash flows from investing activities:	'	'
Proceeds from sales or maturities of investments	26,706	30,663
Purchase of investments	-25,046	-33,906
Proceeds from sale of assets	100	368
Capital expenditures	-124	-23
Change in restricted cash	2,883	'
Net cash provided by (used in) investing activities	4,519	-2,898
Cash flows from financing activities:	'	'
Payment of contingent consideration	-31	'
Proceeds from issuance of convertible debt	200,000	'
Payment of debt issuance costs	-6,361	'
Proceeds from issuance of warrants	25,620	'
Purchase of convertible bond hedges	-39,760	'
Proceeds from the exercise of stock options	1,017	163
Net cash provided by financing activities	180,485	163
Net increase (decrease) in cash and cash equivalents	173,930	-12,448
Cash and cash equivalents at beginning of the period	26,986	46,293
Cash and cash equivalents at end of the period	$200,916	$33,845

Description_of_Business

Description of Business	3 Months Ended
	Mar. 31, 2014
Description of Business	'
Description of Business	'
	A.               Description of Business
	AMAG Pharmaceuticals, Inc., a Delaware corporation, was founded in 1981. We are a specialty pharmaceutical company that markets Feraheme® (ferumoxytol) Injection for Intravenous, or IV, use to treat iron deficiency anemia, or IDA, and MuGard® Mucoadhesive Oral Wound Rinse for the management of oral mucositis.
	Currently, our principal source of revenue is from the sale of Feraheme, which was approved for marketing in the U.S. in June 2009 by the U.S. Food and Drug Administration, or the FDA, for use as an IV iron replacement therapy for the treatment of IDA in adult patients with chronic kidney disease, or CKD. We began selling Feraheme in the U.S. in July 2009 through our own commercial organization, including a specialty sales force. We sell Feraheme to authorized wholesalers and specialty distributors, who in turn, sell Feraheme to healthcare providers who administer Feraheme primarily within hospitals, hematology and oncology centers, and nephrology clinics.
	Outside of the U.S., ferumoxytol has been granted marketing approval in Canada, Switzerland and the European Union, or EU, for use as an IV iron replacement therapy for the treatment of IDA in adult patients with CKD. The European marketing authorization for Rienso in the EU is valid in the 28 EU Member States as well as in Iceland, Liechtenstein and Norway. Under our amended agreement with Takeda Pharmaceutical Company Limited, or Takeda, Takeda has an exclusive license to market and sell ferumoxytol in Canada, the EU and Switzerland, as well as certain other geographic territories. In Canada, Takeda promotes ferumoxytol under the trade name Feraheme and in the EU and Switzerland, Takeda promotes ferumoxytol under the trade name Rienso® 30mg/ml solution for Injection.
	On June 6, 2013, or the Acquisition Date, we entered into a License Agreement with Access Pharmaceuticals, Inc., or Access, under which we acquired the U.S. commercial rights to MuGard, or the Access License Agreement. MuGard was launched in the U.S. by Access in 2010 after receiving 510(k) clearance from the FDA and is indicated for the management of oral mucositis/stomatitis (that may be caused by radiotherapy and/or chemotherapy) and all types of oral wounds (mouth sores and injuries), including aphthous ulcers/canker sores and traumatic ulcers, such as those caused by oral surgery or ill-fitting dentures or braces. Under the Access License Agreement, we obtained an exclusive, royalty-bearing license, with the right to grant sublicenses, to certain intellectual property rights, including know-how, patents and trademarks, to use, import, offer for sale, sell, manufacture and commercialize MuGard in the U.S. and its territories, or the U.S. Territory, for the management of all diseases or conditions of the oropharyngeal cavity, including mucositis, or the MuGard Rights. Additional details regarding the Access License Agreement and the MuGard Rights can be found in Note H, “Business Combination.”
	Throughout this Quarterly Report on Form 10-Q, AMAG Pharmaceuticals, Inc. and our consolidated subsidiaries are collectively referred to as “the Company,” “we,” “us,” or “our.”

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Basis of Presentation and Summary of Significant Accounting Policies	'
Basis of Presentation and Summary of Significant Accounting Policies	'
	B.               Basis of Presentation and Summary of Significant Accounting Policies
	Basis of Presentation
	These condensed consolidated financial statements are unaudited and, in the opinion of management, include all adjustments necessary for a fair statement of the financial position and results of operations of the Company for the interim periods presented. Such adjustments consisted only of normal recurring items. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.
	In accordance with accounting principles generally accepted in the United States of America for interim financial reports and the instructions for Form 10-Q and the rules of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual financial statements have been condensed or omitted. Our accounting policies are described in the Notes to the Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2013. Interim results are not necessarily indicative of the results of operations for the full year. These interim financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2013.
	Use of Estimates and Assumptions
	The preparation of condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities. The most significant estimates and assumptions are used in, but are not limited to, revenue recognition related to product sales and collaboration agreements, product sales allowances and accruals, assessing investments for potential other-than-temporary impairment, determining the fair values of our investments, assets acquired in a business combination, our debt obligations, and contingent consideration, the impairment of long-lived assets, including intangible assets, accrued expenses, and equity-based compensation expense. Actual results could differ materially from those estimates.
	Cash and Cash Equivalents
	Cash and cash equivalents consists principally of cash held in commercial bank accounts, money market funds and U.S. Treasury securities having an original maturity of less than three months. We consider all highly liquid investments with a maturity of three months or less at acquisition date to be cash equivalents. At March 31, 2014, substantially all of our cash and cash equivalents were held in either commercial bank accounts or money market funds.
	Principles of Consolidation
	The accompanying condensed consolidated financial statements include our accounts and the accounts of our wholly-owned subsidiaries, AMAG Europe Limited, AMAG Securities Corporation and Snowbird, Inc. AMAG Europe Limited was incorporated in October 2009 in London, England. AMAG Securities Corporation is a Massachusetts corporation which was incorporated in August 2007. Snowbird, Inc. is a Delaware corporation which was incorporated in December 2013. All intercompany account balances and transactions between the companies have been eliminated.
	Fair Value Measurements
	Under current accounting standards, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.
	Current accounting guidance establishes a hierarchy used to categorize how fair value is measured and which is based on three levels of inputs, of which the first two are considered observable and the third unobservable, as follows:
	Level 1 - Quoted prices in active markets for identical assets or liabilities.
	Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	We hold certain assets and liabilities that are required to be measured at fair value on a recurring basis, including our cash equivalents, investments, and contingent consideration.
	Revenue Recognition and Related Sales Allowances and Accruals
	An analysis of our U.S. Feraheme product sales allowances and accruals for the three months ended March 31, 2014 and 2013 is as follows (in thousands):
		Three Months Ended March 31,
		2014			2013
	Provision for U.S. Feraheme product sales allowances and accruals
	Discounts and chargebacks	$	10,533		$	7,493
	Government and other rebates	3,187			2,387
	Returns	226			193
	Total provision for U.S. Feraheme product sales allowances and accruals	$	13,946		$	10,073
	Total gross U.S. Feraheme product sales	$	31,321		$	25,651
	Total provision for U.S. Feraheme product sales allowances and  accruals as a percent of total gross U.S. Feraheme product sales	45		%	39		%
	Consistent with industry practice, we generally offer our wholesalers, specialty distributors and other customers a limited right to return Feraheme based on the product’s expiration date which, once packaged, is currently five years in the U.S. We estimate product returns based on the historical return patterns and known or expected changes in the marketplace. We currently have limited actual returns data, and therefore are not able to solely rely on our actual returns experience. We track actual returns by individual production lots. Returns on lots eligible for credits under our returned goods policy are monitored and compared with historical return trends and rates.
	We consider several additional factors in our product return estimation process, including our internal sales forecasts and inventory levels in the distribution channel. We expect that wholesalers and healthcare providers will not stock significant inventory due to the cost and expense to store Feraheme. Based on these factors, we determine whether an adjustment to the sales return reserve is appropriate.
	We record an estimate of returns at the time of sale. If necessary, our estimated rate of returns may be adjusted for actual return experience as it becomes available and for known or expected changes in the marketplace. We did not significantly adjust our reserve for product returns during the three months ended March 31, 2014 or 2013. To date, returns of Feraheme have been relatively limited and returns experience may change over time. A future adjustment to our product returns estimate would result in a corresponding change to our net product sales in the period of adjustment and could be significant.
	In addition, as part of our sales allowances and accruals, we reserve for estimated Medicaid rebates associated with instances where Medicaid will act as the insurer and for which we are required to pay a statutory rebate to Medicaid. We regularly assess our Medicaid reserve balance and the rate at which we accrue for claims against product sales. We did not adjust our Medicaid reserve balance during the three months ended March 31, 2014 or 2013. If we determine in future periods that our actual rebate experience is not indicative of expected claims, if our actual claims experience changes, or if other factors affect estimated claims rates, we may be required to adjust our current Medicaid accumulated reserve estimate, which would affect our net product sales in the period of the adjustment and could be significant.
	Concentrations and Significant Customer Information
	Financial instruments which potentially subject us to concentrations of credit risk consist principally of cash, investments, and accounts receivable. As of March 31, 2014, our cash, cash equivalents and investments amounted to approximately $385.5 million. We currently invest our excess cash primarily in U.S. government and agency money market funds, and investments in corporate debt securities, U.S. treasury and government agency securities, and commercial paper. As of March 31, 2014, we had approximately $196.3 million of our total $200.9 million cash and cash equivalents balance invested in institutional money market funds, of which $179.9 million was invested in a single fund.
	Our operations are located solely within the U.S. We are focused principally on developing, manufacturing, and commercializing Feraheme/Rienso and commercializing MuGard. We perform ongoing credit evaluations of our customers and generally do not require collateral. The following table sets forth customers who represented 10% or more of our total revenues for the three months ended March 31, 2014 and 2013:
		Three Months Ended March 31,
		2014		2013
	AmerisourceBergen Drug Corporation	39	%	43	%
	McKesson Corporation	22	%	22	%
	Cardinal Health, Inc.	15	%	15	%
	Takeda Pharmaceuticals Company Limited	11	%	12	%
	In addition, approximately 28% and 30% of our end-user demand during the three months ended March 31, 2014 and 2013, respectively, was generated by members of a single group purchasing organization, or GPO, with which we have contracted. Revenues from customers outside of the U.S. amounted to approximately 16% and 12% of our total revenues for the three months ended March 31, 2014 and 2013, respectively, and were principally related to collaboration revenue recognized in connection with our collaboration agreement with Takeda, which is headquartered in Japan.
	We are currently solely dependent on a single supply chain for our Feraheme/Rienso drug substance and finished drug product. We are exposed to a significant loss of revenue from the sale of Feraheme/Rienso if our suppliers and/or manufacturers cannot fulfill demand for any reason.

Investments

Investments	3 Months Ended
	Mar. 31, 2014
Investments	'
Investments	'
	C.            Investments
	As of March 31, 2014 and December 31, 2013, our investments equaled $184.6 million and $186.8 million, respectively, and consisted of securities classified as available-for-sale in accordance with accounting standards which provide guidance related to accounting and classification of certain investments in debt and equity securities.
	The following is a summary of our investments as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Corporate debt securities
	Due in one year or less	$	23,492	$	46	$	(2	)	$	23,536
	Due in one to three years	108,536		159		(47		)	108,648
	U.S. treasury and government agency securities
	Due in one year or less	21,079		35		—			21,114
	Due in one to three years	29,772		17		(28		)	29,761
	Commercial paper
	Due in one year or less	1,499		—		(1		)	1,498
	Total investments	$	184,378	$	257	$	(78	)	$	184,557
		December 31, 2013
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Corporate debt securities
	Due in one year or less	$	42,609	$	44	$	(4	)	$	42,649
	Due in one to three years	91,443		137		(106		)	91,474
	U.S. treasury and government agency securities
	Due in one year or less	18,526		19		—			18,545
	Due in one to three years	34,123		37		(25		)	34,135
	Total investments	$	186,701	$	237	$	(135	)	$	186,803
	Impairments and Unrealized Gains and Losses on Investments
	We did not recognize any other-than-temporary impairment losses in our condensed consolidated statements of operations related to our securities during the three months ended March 31, 2014 and 2013. We considered various factors, including the length of time that each security was in an unrealized loss position and our ability and intent to hold these securities until the recovery of their amortized cost basis occurs. As of March 31, 2014, an insignificant portion of our investments has been in an unrealized loss position for more than one year. Future events may occur, or additional information may become available, which may cause us to identify credit losses where we do not expect to receive cash flows sufficient to recover the entire amortized cost basis of a security and which may necessitate the recording of future realized losses on securities in our portfolio. Significant losses in the estimated fair values of our investments could have a material adverse effect on our earnings in future periods.
	Realized Gains and Losses on Investments
	Gains and losses are determined on the specific identification method. Realized gains were insignificant during the three months ended March 31, 2014 and 2013.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Fair Value Measurements	'
	D.            Fair Value Measurements
	The following tables represent the fair value hierarchy as of March 31, 2014 and December 31, 2013 for those assets and liabilities that we measure at fair value on a recurring basis (in thousands):
		Fair Value Measurements at March 31, 2014 Using:
					Quoted Prices in Active		Significant Other		Significant
					Markets for Identical		Observable Inputs		Unobservable
					Assets				Inputs
		Total			(Level 1)		(Level 2)		(Level 3)
	Assets:
	Money market funds	$	196,297		$	196,297	$	—	$	—
	Corporate debt securities	132,184			$	—	132,184		—
	U.S. treasury and government agency securities	50,875			$	—	50,875		—
	Commercial paper	1,498			—		1,498		—
	Total Assets	$	380,854		$	196,297	$	184,557	$	—
	Liabilities:
	Acquisition-related contingent consideration	$	15,382		—		—		15,382
	Total Liabilities	$	15,382		$	—	$	—	$	15,382
		Fair Value Measurements at December 31, 2013 Using:
					Quoted Prices in Active		Significant Other		Significant
					Markets for Identical		Observable Inputs		Unobservable
					Assets				Inputs
		Total			(Level 1)		(Level 2)		(Level 3)
	Assets:
	Money market funds	$	18,767		$	18,767	$	—	$	—
	Corporate debt securities	134,123			—		134,123		—
	U.S. treasury and government agency securities	52,680			—		52,680		—
	Total Assets	$	205,570		$	18,767	$	186,803	$	—
	Liabilities:
	Acquisition-related contingent consideration	$	14,550		$	—	$	—	$	14,550
	Total Liabilities	$	14,550		$	—	$	—	$	14,550
	With the exception of our money market funds and our acquisition-related contingent consideration, the fair value of our investments is primarily determined from independent pricing services. Independent pricing services normally derive security prices from recently reported trades for identical or similar securities, making adjustments based upon other significant observable market transactions. At the end of each reporting period, we perform quantitative and qualitative analyses of prices received from third parties to determine whether prices are reasonable estimates of fair value. After completing our analyses, we did not adjust or override any fair value measurements provided by our pricing services as of March 31, 2014. In addition, there were no transfers or reclassifications of any securities between Level 1 and Level 2 during the three months ended March 31, 2014.
	Contingent consideration
	We are accounting for the acquisition of the MuGard Rights as a business combination under the acquisition method of accounting. Additional details regarding the Access License Agreement and the MuGard Rights can be found in Note H. The fair value measurements of contingent consideration obligations arising from business combinations are determined using unobservable, or Level 3, inputs. These inputs include (a) the estimated amount and timing of projected cash flows; (b) the probability of the achievement of the factors on which the contingency is based; and (c) the risk-adjusted discount rate used to present value the probability-weighted cash flows. Significant increases (decreases) in any of those inputs in isolation could result in a significantly lower or higher fair value measurement.
	The following table presents a reconciliation of contingent consideration obligations related to our acquisition of the MuGard Rights measured on a recurring basis using Level 3 inputs as of March 31, 2014 (in thousands):
	Balance as of December 31, 2013	$	14,550
	Payments made	(31		)
	Adjustments to fair value of contingent consideration	789
	Other adjustments	74
	Balance as of March 31, 2014	$	15,382
	During the three months ended March 31, 2014, we recorded $0.8 million in expense related to the increase in fair value of the contingent consideration liability. This expense principally represents the time value of money impact of the contingent consideration fair value assessment as of March 31, 2014 and is included in selling, general and administrative expenses in our condensed consolidated statements of operations. As of March 31, 2014, we estimate that the undiscounted royalty amounts we could pay under the Access License Agreement may range from $28.0 million to $34.0 million over a ten year period, which is our best estimate of the period over which we expect the majority of the asset’s cash flows to be derived. This measure is based on significant Level 3 inputs not observable in the market. Key assumptions include a discount rate of approximately 15%. We have classified $1.3 million of the contingent consideration as a short-term liability, which was included in accrued expenses in our condensed consolidated balance sheet as of March 31, 2014.
	Debt
	In February 2014, we issued $200.0 million of 2.5% convertible senior notes due February 15, 2019, or the Convertible Notes. Interest is payable semi-annually in arrears on February 15 and August 15 of each year, beginning on August 15, 2014. The fair value of our Convertible Notes, which differs from their carrying values, is influenced by interest rates and our stock price and stock price volatility and is determined by prices for the Convertible Notes observed in market trading, which are Level 2 inputs. The estimated fair value of the Convertible Notes at March 31, 2014 was $161.8 million. In addition, in connection with the pricing of the Convertible Notes, we entered into convertible bond hedge transactions, or convertible bond hedges, and separate warrant transactions, or warrants, as discussed in more detail in Note P, “Debt.” The carrying value of long-term debt approximated fair value at March 31, 2014 due to the recent issuance of the Convertible Notes.

Accounts_Receivable_Net

Accounts Receivable, Net	3 Months Ended
	Mar. 31, 2014
Accounts Receivable, Net	'
Accounts Receivable, Net	'
	E.           Accounts Receivable, Net
	Our net accounts receivable were $10.1 million and $6.8 million as of March 31, 2014 and December 31, 2013, respectively, and primarily represented amounts due from wholesalers and distributors to whom we sell Feraheme directly. Accounts receivable are recorded net of reserves for estimated chargeback obligations, prompt payment discounts and any allowance for doubtful accounts.
	Customers which represented greater than 10% of our accounts receivable balances as of March 31, 2014 and December 31, 2013 were as follows:
		March 31, 2014		December 31, 2013
	AmerisourceBergen Drug Corporation	52	%	49	%
	McKesson Corporation	27	%	27	%
	Cardinal Health, Inc.	15	%	16	%

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventories	'
Inventories	'
	F.             Inventories
	Our major classes of inventories were as follows as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014		December 31, 2013
	Raw materials	$	4,116	$	3,157
	Work in process	8,929		8,322
	Finished goods	7,759		5,738
	Total inventories	$	20,804	$	17,217
	During the three months ended March 31, 2014, we expensed $1.1 million of commercial inventory, which we determined would be solely used in manufacturing process and development activities at our third-party suppliers, which we have recorded in research and development expenses. In addition, we expensed $0.3 million of commercial inventory deemed no longer saleable, which we have recorded in cost of goods sold.

Property_and_Equipment_Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2014
Property and Equipment, Net	'
Property and Equipment, Net	'
	G.           Property and Equipment, Net
	Property and equipment consisted of the following as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014			December 31, 2013
	Furniture and fixtures	$	1,489		$	1,536
	Leasehold improvements	430			430
	Laboratory and production equipment	493			376
		2,412			2,342
	Less - accumulated depreciation	(575		)	(496		)
	Property and equipment, net	$	1,837		$	1,846

Business_Combination

Business Combination	3 Months Ended
	Mar. 31, 2014
Business Combination	'
Business Combination	'
	H.           Business Combination
	As part of our strategy to expand our portfolio with additional commercial-stage specialty products, in June 2013, we entered into the Access License Agreement pursuant to which we obtained an exclusive, royalty-bearing license, with the right to grant sublicenses, to certain intellectual property rights, including know-how, patents and trademarks, to use, import, offer for sale, sell, manufacture and commercialize MuGard in the U.S. Territory for the management of all diseases or conditions of the oropharyngeal cavity, including mucositis.
	In consideration for the license, we paid Access an upfront payment of $3.3 million in June 2013. We are required to pay royalties to Access on future net sales of MuGard until the later of (a) the expiration of the licensed patents or (b) the tenth anniversary of the first commercial sale of MuGard under the Access License Agreement in the U.S. Territory, or the Royalty Term. These tiered, double-digit royalty rates decrease for any part of the Royalty Term occurring after the expiration of the licensed patents and are subject to off-set against certain of our expenses. After the expiration of the Royalty Term, the license shall become a fully paid-up, royalty-free and perpetual license in the U.S. Territory. In addition to making an upfront payment of $3.3 million, we also acquired $0.2 million of existing MuGard inventory from Access, which was included in our condensed consolidated balance sheet as of the Acquisition Date.
	We did not assume any pre-existing liabilities related to the MuGard business, contingent or otherwise, arising prior to the Acquisition Date. We are accounting for the acquisition of the MuGard Rights as a business combination under the acquisition method of accounting. The following table summarizes the total consideration for the MuGard Rights (in thousands):
	Consideration:
	Cash	$	3,434
	Acquisition-related contingent consideration	13,700
	Total consideration	$	17,134
	The $17.1 million total consideration includes the estimated fair value of the contingent consideration at the Acquisition Date.
	The following table summarizes the estimated fair values of the assets acquired related to the business combination as of the Acquisition Date (in thousands):
	Assets Acquired:
	MuGard intangible asset	$	16,893
	Inventory	241
	Net identifiable assets acquired	$	17,134
	Transaction costs are not included as a component of consideration transferred and are expensed as incurred. We incurred approximately $0.8 million of acquisition-related costs in the second quarter of 2013. These costs were primarily related to professional and legal fees and are included in selling, general and administrative expenses in our condensed consolidated statements of operations for the second quarter of 2013.

Intangible_Assets_Net

Intangible Assets, Net	3 Months Ended
	Mar. 31, 2014
Intangible Assets, Net	'
Intangible Assets, Net	'
	I.                   Intangible Assets, Net
	In June 2013, we acquired the MuGard Rights from Access and recorded $16.9 million to finite-lived intangible assets based on the estimated fair value of the MuGard Rights as of the Acquisition Date.
	We will amortize the MuGard Rights using an economic consumption model over ten years, which represents our best estimate of the period over which we expect the majority of the asset’s cash flows to be derived. We believe this is the best approximation of the period over which we will derive the majority of value of the MuGard Rights. We recorded less than $0.1 million of amortization related to the MuGard Rights in cost of product sales in our condensed consolidated statements of operations for the three months ended March 31, 2014 and as a result, our intangible asset related to the MuGard Rights was $16.8 million as of March 31, 2014.
	Intangible assets are reviewed for impairment at least annually and whenever facts or circumstances suggest that the carrying value of these assets may not be recoverable. Our policy is to identify and record impairment losses, if necessary, on intangible assets when events and circumstances indicate that the assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amounts of those assets.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Taxes	'
Income Taxes	'
	J.                 Income Taxes
	Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using future enacted rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized.
	For the three months ended March 31, 2014 and 2013, we did not recognize any tax expense or benefit due to our continued net operating loss position. Due to the uncertainty surrounding the realization of favorable tax attributes in future tax returns, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets.
	The interest expense related to the Convertible Notes is deductible for income tax purposes, subject to certain limitations.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Loss	'
Accumulated Other Comprehensive Loss	'
	K.           Accumulated Other Comprehensive Loss
	The changes in accumulated other comprehensive loss, net of tax, for the three months ended March 31, 2014 and 2013 consisted of the following (in thousands):
		Three Months Ended March 31,
		2014			2013
	Beginning Balance	$	(3,491	)	$	(3,247	)
	Other comprehensive income (loss) before reclassifications	77			(87		)
	Gain (loss) reclassified from other accumulated comprehensive loss	—			(6		)
	Ending Balance	$	(3,414	)	$	(3,340	)
	The amounts reclassified from other comprehensive loss for the three months ended March 31, 2014, primarily represented realized gains on investments, which are included in our condensed consolidated statement of operations under “Gains on investments, net.”

Net_Loss_per_Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2014
Net Loss per Share	'
Net Loss per Share	'
	L.            Net Loss per Share
	We compute basic net loss per share by dividing net loss by the weighted average number of common shares outstanding during the relevant period.
	In February 2014, in connection with the issuance of the Convertible Notes, we entered into convertible bond hedges. The convertible bond hedges are not included for purposes of calculating the number of diluted shares outstanding, as their effect would be anti-dilutive. The convertible bond hedges are generally expected, but not guaranteed, to reduce the potential dilution and/or offset the cash payments we are required to make upon conversion of the Convertible Notes. See Note P, “Debt,” for additional information. As we have a choice to settle the conversion obligation under the Convertible Notes in cash, shares or any combination of the two, we have determined that we intend to settle the accreted principal value of the Convertible Notes in cash and the excess conversion premium in shares. While the dilutive effect of the conversion premium will be considered in the calculation of diluted net income per share using the treasury stock method, the accreted principal value of the Convertible Notes will not be included in the calculation of diluted income per share, as we intend to settle this in cash.
	The components of basic and diluted net loss per share were as follows (in thousands, except per share data):
		Three Months Ended March 31,
		2014			2013
	Net loss	$	(7,102	)	$	(3,895	)
	Weighted average common shares outstanding	21,824			21,544
	Net loss per share:
	Basic and diluted	$	(0.33	)	$	(0.18	)
	The following table sets forth the potential common shares issuable upon the exercise of outstanding options, the vesting of RSUs and warrants (prior to consideration of the treasury stock method), which were excluded from our computation of diluted net loss per share because such instruments were anti-dilutive (in thousands):
		Three Months Ended March 31,
		2014		2013
	Options to purchase shares of common stock	3,335		2,750
	Shares of common stock issuable upon the vesting of restricted stock units	481		510
	Warrants	7,382		—
	Total	11,198		3,260
	We have determined that we have the intent and ability to settle the debt component of the Convertible Notes in cash and the excess conversion spread in shares. Therefore, the effect of the Convertible Notes reflected in diluted earnings per share is limited to the conversion premium, which is reflected in the calculation of diluted earnings per share as if it were a freestanding written call option on our shares. During the three months ended March 31, 2014, the weighted average common stock price was below the conversion price of the Convertible Notes.
	The dilutive effect of the stock options, RSUs, and warrants is calculated using the treasury stock method. During the three months ended March 31, 2014, the warrants were excluded from diluted shares outstanding because the weighted average common stock price was below the exercise price.

EquityBased_Compensation

Equity-Based Compensation	3 Months Ended
	Mar. 31, 2014
Equity-Based Compensation	'
Equity-Based Compensation	'
	M.            Equity-Based Compensation
	We currently maintain two equity compensation plans, including our Third Amended and Restated 2007 Equity Incentive Plan, or the 2007 Plan, and our Amended and Restated 2000 Stock Plan, or the 2000 Plan. During the three months ended March 31, 2014, we also granted equity to certain newly hired executive officers through inducement grants outside of these plans.
	Third Amended and Restated 2007 Equity Incentive Plan
	Our 2007 Plan was originally approved by our stockholders in November 2007. In each of May 2009, May 2010, and May 2013 our stockholders approved proposals to amend and restate our 2007 Plan to, among other things, increase the number of shares authorized for issuance thereunder by 600,000, 800,000 and 1,100,000 shares, respectively.
	As of March 31, 2014, we have granted options and RSUs covering 7,076,175 shares of common stock under our 2007 Plan, of which 2,712,957 stock options and 661,811 RSUs have expired or terminated, and of which 210,524 options have been exercised and 500,871 shares of common stock have been issued pursuant to RSUs that became fully vested. The number of options and RSUs outstanding under this plan as of March 31, 2014, was 2,684,438 and 305,574, respectively. The remaining number of shares available for future grants as of March 31, 2014 was 1,514,760, not including shares subject to outstanding awards under the 2000 Plan, which will be added to the total number of shares available for issuance under the 2007 Plan to the extent that such awards expire or terminate for any reason prior to exercise. All outstanding stock options granted under our 2007 Plan have an exercise price equal to the closing price of a share of our common stock on the grant date and have either a seven or ten-year term.
	Amended and Restated 2000 Stock Plan
	Our 2000 Plan provided for the grant of options and other equity-based awards to our directors, officers, employees and consultants. The terms and conditions of each such grant, including, but not limited to, the number of shares, the exercise price, term of the option/award and vesting requirements, were determined by our Board or the Compensation Committee of our Board. As of March 31, 2014, we have granted stock options and RSUs covering 2,182,700 shares of common stock under the 2000 Plan, of which 984,339 stock options and 1,500 RSUs have expired or terminated, and of which 1,052,045 stock options have been exercised and 42,500 shares of common stock have been issued pursuant to RSUs that became fully vested. The remaining number of shares underlying outstanding stock options which were issued pursuant to our 2000 Plan as of March 31, 2014, was 102,316. There were no remaining restricted RSUs which were issued pursuant to our 2000 Plan as of March 31, 2014. All outstanding stock options granted under the 2000 Plan have an exercise price equal to the closing price of our common stock on the grant date and have a ten year term. In November 2007, the 2000 Plan was succeeded by our 2007 Plan and, accordingly, no further grants may be made under this plan. Any shares that remained available for issuance under the 2000 Plan as of the date of adoption of the 2007 Plan are included in the number of shares that may be issued under the 2007 Plan. Any shares subject to outstanding awards granted under the 2000 Plan that expire or terminate for any reason prior to exercise will be added to the total number of shares available for issuance under the 2007 Plan.
	Other Equity Compensation Grants
	During the three months ended March 31, 2014, our Board granted options to purchase 90,000 shares of our common stock to certain members of our senior management to induce them to accept employment with us. These options were granted at an exercise price equal to the fair market value of a share of our common stock on the respective grant dates. The options will be exercisable in four equal annual installments beginning on the first anniversary of the respective grant dates. In addition, during the three months ended March 31, 2014, our Board granted 35,000 RSUs to certain members of our senior management to induce them to accept employment with us. These grants will vest in four equal annual installments beginning on the first anniversary of the respective grant dates. The foregoing grants were made pursuant to inducement grants outside of our 2007 Plan as permitted under the NASDAQ Global Market rules. We assessed the terms of these awards and determined there was no possibility that we would have to settle these awards in cash and therefore, equity accounting was applied.
	Equity-based compensation expense
	Equity-based compensation expense for the three months ended March 31, 2014 and 2013, consisted of the following (in thousands):
		Three Months Ended March 31
		2014		2013
	Cost of product sales	$	28	$	23
	Research and development	449		932
	Selling, general and administrative	1,453		1,328
	Total equity-based compensation expense	$	1,930	$	2,283
	We reduce the compensation expense being recognized to account for estimated forfeitures, which we estimate based primarily on historical experience, adjusted for unusual events such as corporate restructurings, which may result in higher than expected turnover and forfeitures. Under current accounting guidance, forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
Commitments and Contingencies	'
	N.               Commitments and Contingencies
	Legal Proceedings
	We accrue a liability for legal contingencies when we believe that it is both probable that a liability has been incurred and that we can reasonably estimate the amount of the loss. We review these accruals and adjust them to reflect ongoing negotiations, settlements, rulings, advice of legal counsel and other relevant information. To the extent new information is obtained and our views on the probable outcomes of claims, suits, assessments, investigations or legal proceedings change, changes in our accrued liabilities would be recorded in the period in which such determination is made. For the matters referenced below, the liability is not probable or the amount cannot be reasonably estimated and, therefore, accruals have not been made. In addition, in accordance with the relevant authoritative guidance, for any matters in which the likelihood of material loss is at least reasonably possible, we will provide disclosure of the possible loss or range of loss. If a reasonable estimate cannot be made, however, we will provide disclosure to that effect.
	A purported class action complaint was originally filed on March 18, 2010 in the U.S. District Court for the District of Massachusetts, entitled Silverstrand Investments et. al. v. AMAG Pharm., Inc., et. al., Civil Action No. 1:10-CV-10470-NMG, and was amended on September 15, 2010 and on December 17, 2010. The second amended complaint, or SAC, filed on December 17, 2010 alleged that we and our former President and Chief Executive Officer, former Chief Financial Officer, the then-members of our Board, and certain underwriters in our January 2010 offering of common stock violated certain federal securities laws, specifically Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, and that our former President and Chief Executive Officer and former Chief Financial Officer violated Section 15 of such Act, respectively, by making certain alleged omissions in a registration statement filed in January 2010. The plaintiffs sought unspecified damages on behalf of a purported class of purchasers of our common stock pursuant to our common stock offering on or about January 21, 2010. On August 11 and 15, 2011, respectively, the District Court issued an Opinion and Order dismissing the SAC with prejudice for failure to state a claim upon which relief could be granted. On September 14, 2011, the plaintiffs filed a Notice of Appeal to the U.S. Court of Appeals for the First Circuit, or the Court of Appeals. The Court of Appeals heard oral argument on May 11, 2012. On February 4, 2013, the Court of Appeals affirmed in part and reversed in part the District Court’s Opinion and Order and remanded the case to the District Court. On February 19, 2013, we filed a Petition for Panel Rehearing and Rehearing En Banc, which was denied on March 15, 2013. On March 22, 2013, we filed a Motion to Stay the Mandate remanding the case to the District Court pending review by the U.S. Supreme Court of the Court of Appeals’ February 4, 2013 decision. The Court of Appeals granted the Motion to Stay the Mandate on April 8, 2013. On June 13, 2013, we filed a Petition for a Writ of Certiorari, or the Petition, with the U.S. Supreme Court seeking review of the Court of Appeal’s decision and to have that decision overturned. On October 7, 2013 the U.S. Supreme Court denied our Petition, resulting in the case’s return to the District Court for further proceedings relative to the SAC’s surviving claims. On November 6, 2013, we filed a renewed Motion to Dismiss the SAC’s surviving claims. On December 6, 2013, the plaintiffs filed a brief in opposition to our Motion to Dismiss and we filed a reply brief in support of our Motion on December 27, 2013. On April 7, 2014, the District Court denied our renewed Motion to Dismiss. A status conference is scheduled for May 14, 2014. We are currently unable to predict the outcome or reasonably estimate the range of potential loss associated with this matter, if any, and have therefore not recorded any potential estimated liability as we do not believe that such a liability is probable nor do we believe that a range of loss is currently estimable.
	In July 2010, Sandoz GmbH, or Sandoz, filed with the European Patent Office, or the EPO, an opposition to a previously issued patent which covers ferumoxytol in EU jurisdictions. In October 2012, at an oral hearing, the Opposition Division of the EPO revoked this patent. In December 2012, our notice of appeal of that decision was recorded with the EPO, which also suspended the revocation of our patent. On May 13, 2013, we filed a statement of grounds of appeal and on September 27, 2013, Sandoz filed a response to that statement. We filed a reply to that response on March 17, 2014. We will continue to defend the validity of this patent throughout the appeals process, which we expect to take two to three years. However, in the event that we do not experience a successful outcome from the appeals process, under EU regulations ferumoxytol would still be entitled to eight years of data protection and ten years of market exclusivity from the date of approval, which we believe would create barriers to entry for any generic version of ferumoxytol into the EU market until sometime between 2020 and 2022. This decision had no impact on our revenues for the three months ended March 31, 2014. However, any future unfavorable outcome in this matter could negatively affect the magnitude and timing of future revenues, including royalties and milestone payments we may receive from Takeda pursuant to our collaboration agreement with Takeda. We do not expect to incur any related liability regardless of the outcome of the appeal and therefore have not recorded any liability as of March 31, 2014. We continue to believe the patent is valid and intend to vigorously appeal the decision.
	We may periodically become subject to other legal proceedings and claims arising in connection with ongoing business activities, including claims or disputes related to patents that have been issued or that are pending in the field of research on which we are focused. Other than the above actions, we are not aware of any material claims against us at March 31, 2014. We expense legal costs as they are incurred.

Collaborative_Agreements

Collaborative Agreements	3 Months Ended
	Mar. 31, 2014
Collaborative Agreements	'
Collaborative Agreements	'
	O.           Collaborative Agreements
	Our commercial strategy includes the formation of collaborations with other pharmaceutical companies to facilitate the sale and distribution of Feraheme/Rienso, primarily outside of the U.S., as well as expanding our portfolio through the in-license or purchase of additional specialty pharmaceutical products.
	Takeda
	In March 2010, we entered into the Takeda Agreement with Takeda under which we granted exclusive rights to Takeda to develop and commercialize Feraheme/Rienso as a therapeutic agent in Europe, certain Asia-Pacific countries (excluding Japan, China and Taiwan), the Commonwealth of Independent States, Canada, India and Turkey. In June 2012, we entered into an amendment to the Takeda Agreement, or the Amended Takeda Agreement, which removed the Commonwealth of Independent States from the territories under which Takeda has the exclusive rights to develop and commercialize Feraheme/Rienso. In addition, the Amended Takeda Agreement modified the timing and pricing arrangements for a supply agreement to be entered into between us and Takeda, and which was entered into in February 2014 and discussed below, the terms related to primary and secondary manufacturing for drug substance and drug product, certain patent-related provisions, and the re-allocation of certain of the agreed-upon milestone payments. We analyzed the Amended Takeda Agreement and determined that the amended terms did not result in a material modification of the original Takeda Agreement (and thus did not require us to change our accounting model) because (a) there were no changes to the deliverables under the original Takeda Agreement as a result of the amendment, and (b) the change in arrangement consideration as a result of the amendment was not quantitatively material in relation to the total arrangement consideration.
	In connection with the execution of the original Takeda Agreement, we received a $60.0 million upfront payment from Takeda in April 2010, which we recorded as deferred revenue, as well as approximately $1.0 million reimbursed to us during 2010 for certain expenses incurred prior to entering the agreement, which we considered an additional upfront payment. Because we cannot reasonably estimate the total level of effort required to complete the obligations under the combined deliverable, we are recognizing the entire $60.0 million upfront payment, the $1.0 million reimbursed to us in 2010, as well as any non-substantive milestone payments that are achieved into revenues on a straight-line basis over a period of ten years from March 31, 2010, the date on which we originally entered the Takeda Agreement, which represents the then-current patent life of Feraheme/Rienso and our best estimate of the period over which we will substantively perform our obligations. We continue to believe that the then-current patent life of Feraheme/Rienso is our best estimate of the period over which we will substantively perform our obligations under this agreement.
	In addition, the remaining milestone payments we may be entitled to receive under the Amended Takeda Agreement could over time equal up to $186.0 million. For any milestone payments we may receive based upon the approval by certain regulatory agencies, we have determined that these will be deemed substantive milestones and, therefore, will be accounted for as revenue in the period in which they are achieved. We have also determined that any non-substantive milestone payments will be accounted for in accordance with our revenue attribution method for the upfront payment, as described above. During the three months ended March 31, 2014, we recorded $2.0 million in revenues associated with the amortization of the upfront payments in license fee and other collaboration revenues in our condensed consolidated statement of operations. Any potential non-substantive milestone payments that may be received in the future will be recognized as revenue on a cumulative catch up basis when they become due and payable.
	Under the terms of the Amended Takeda Agreement, Takeda is responsible for reimbursing us for certain out-of-pocket regulatory and clinical trial supply costs associated with carrying out our regulatory and clinical research activities under the collaboration agreement. Because we are acting as the principal in carrying out these services, any reimbursement payments received from Takeda are recorded in license fee and other collaboration revenues in our condensed consolidated statement of operations to match the costs that we incur during the period in which we perform those services. We recorded $0.1 million and less than $0.1 million for the three months ended March 31, 2014 and 2013, respectively, associated with other reimbursement revenues received from Takeda.
	At the time of shipment, we defer recognition of all revenue for Feraheme/Rienso sold to Takeda in our condensed consolidated balance sheets. We recognize revenues from product sales to Takeda, the related cost of goods sold, and any royalty revenues due from Takeda, in our condensed consolidated statement of operations at the time Takeda reports to us that sales have been made its customers. During the three months ended March 31, 2014, we recognized $0.2 million in product sales and royalty revenue related to the Amended Takeda Agreement and we have included this revenue in other product sales and royalties in our condensed consolidated statement of operations. As of March 31, 2014, we had approximately $2.3 million in deferred revenue related to product shipped to Takeda but not yet sold through to Takeda’s customers, of which $1.2 million was classified as short-term and $1.1 million was classified as long-term. In addition, we had $2.2 million in deferred cost of product sales, of which $1.1 million was classified as short-term and $1.1 million was classified as long-term. These deferred revenue and deferred cost of product sales are recorded in our condensed consolidated balance sheet as of March 31, 2014.
	In February 2014, we entered into a Supply Agreement with Takeda pursuant to which we will sell Feraheme to Takeda, to meet Takeda’s requirements for commercial use of Feraheme in the Licensed Territory. Under the Supply Agreement, Takeda is obligated to periodically provide us with demand forecasts of Takeda’s future Feraheme requirements, which will direct the forecasting and ordering process as well as our supply obligations. Takeda may order Feraheme for commercial use in excess of the forecasts, which we will use commercially reasonable efforts to supply. In addition, the Supply Agreement provides the minimum quantity of Feraheme that shall be ordered in each purchase order for commercial supply. Takeda shall have the right to use the Feraheme ordered under the Supply Agreement for clinical use, provided that the product be subject to all of the terms of the Supply Agreement, including commercial specifications. Takeda shall be solely responsible for labeling and packaging vials of the product in accordance with the terms of the Supply Agreement and the Amended Takeda Agreement. If we are unable, for any reason beyond our reasonable control (including an unanticipated increase in demand beyond the production capacity of the manufacturing sites), to supply sufficient quantities of Feraheme, we agree to promptly establish an allocation procedure with respect to the available supply of Feraheme for the Licensed Territory and outside the Licensed Territory. Takeda may obtain Feraheme from a designated second source established by us if necessary to meet increased demand, or upon the occurrence of certain defined insolvency events. If we are unable to perform its supply obligations under the Supply Agreement after a negotiated period of time following an insolvency event, Takeda can seek permanent alternative supply sources and the parties’ supply and purchase obligations under the Supply Agreement will terminate. The Supply Agreement provides that it will otherwise remain in place for the duration of the Amended Takeda Agreement.
	The Supply Agreement provides pricing terms and also provides that Takeda will reimburse us for certain capital expenditures and shall pay us a per-vial manufacturing fee. In addition, the Supply Agreement specifies cost-sharing arrangements relating to future process changes or improvements to the manufacturing process for Feraheme. We generally agree to indemnify Takeda and its affiliates for damages resulting from the willful misconduct or gross negligence by us or a designated second source with respect to the manufacture of Feraheme, or resulting from our breach of the Supply Agreement. Takeda generally agrees to indemnify us, our affiliates and any designated second source for damages resulting with respect to the manufacture of Feraheme by Takeda or its affiliates, or resulting from Takeda’s breach of the Supply Agreement. The Supply Agreement includes quality control and testing terms, representations and warranties of the parties and other provisions customary for an agreement of this type.
	3SBio, Inc.
	In 2008, we entered into a Collaboration and Exclusive License Agreement with 3SBio Inc., or 3SBio, for the development and commercialization of Feraheme as an IV iron replacement therapeutic agent in China. In consideration of the grant of the license, we received an upfront payment of $1.0 million. In late January 2014, we mutually terminated the agreement with 3SBio, effective immediately, due to the fact that, despite the best efforts of the parties, regulatory approval in China could not be obtained within the agreed upon time period. During the three months ended March 31, 2014, we recognized the $1.0 million upfront payment into revenue as we have no future continuing obligations and have included it in license fee and other collaboration revenues in our condensed consolidated statements of operations.
	Access
	Please refer to Note H, “Business Combinations,” for a detailed description of the Access License Agreement.

Debt

Debt	3 Months Ended
	Mar. 31, 2014
Debt	'
Debt	'
	P.             Debt
	2.5% Convertible Notes
	On February 14, 2014, we issued $200.0 million aggregate principal amount of Convertible Notes, which includes $25.0 million principal amount of Convertible Notes issued pursuant to the full exercise of an over-allotment option granted to the underwriters in the offering. We received net proceeds of $193.3 million from the sale of the Convertible Notes, after deducting fees and expenses of $6.7 million. We used $14.1 million of the net proceeds from the sale of the Convertible Notes to pay the cost of the convertible bond hedges, as described below (after such cost was partially offset by the proceeds to us from the sale of warrants in the warrant transactions described below).
	The Convertible Notes are governed by the terms of an indenture between us, as issuer, and Wilmington Trust, National Association, as the trustee. The Convertible Notes are senior unsecured obligations and bear interest at a rate of 2.5% per year, payable semi-annually in arrears on February 15 and August 15 of each year, beginning on August 15, 2014. The Convertible Notes will mature on February 15, 2019, unless earlier repurchased or converted. The Convertible Notes will be convertible into cash, shares of our common stock, or a combination thereof, at our election, at an initial conversion rate of approximately 36.9079 shares of common stock per $1,000 principal amount of the Convertible Notes, which corresponds to an initial conversion price of approximately $27.09 per share of our common stock and represents a conversion premium of approximately 35% based on the last reported sale price of our common stock of $20.07 on February 11, 2014, the date the notes offering was priced.
	The conversion rate is subject to adjustment from time to time upon the occurrence of certain events, including, but not limited to, the issuance of stock dividends and payment of cash dividends. At any time prior to the close of business on the business day immediately preceding May 15, 2018, holders may convert their Convertible Notes at their option only under the following circumstances:
	(1)         during any calendar quarter commencing after the calendar quarter ended on March 31, 2014 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day;
	(2)         during the five business day period after any five consecutive trading day period, or the measurement period, in which the trading price per $1,000 principal amount of the Convertible Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such trading day; or
	(3)         upon the occurrence of specified corporate events. On or after May 15, 2018 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their Convertible Notes, in multiples of $1,000 principal amount, at the option of the holder regardless of the foregoing circumstances.
	If a make-whole fundamental change, as described in the indenture, occurs and a holder elects to convert its Convertible Notes in connection with such make-whole fundamental change, such holder may be entitled to an increase in the conversion rate as described in the indenture.
	We may not redeem the Convertible Notes prior to the maturity date and no “sinking fund” is provided for the Convertible Notes, which means that we are not required to periodically redeem or retire the Convertible Notes. Upon the occurrence of certain fundamental changes involving us, holders of the Convertible Notes may require us to repurchase for cash all or part of their Convertible Notes at a repurchase price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest.
	The indenture does not contain any financial or maintenance covenants or restrictions on the payments of dividends, the incurrence of indebtedness or the issuance or repurchase of securities by us or any of our subsidiaries. The indenture contains customary terms and covenants and events of default. If an event of default (other than certain events of bankruptcy, insolvency or reorganization involving us) occurs and is continuing, the Trustee by notice to us, or the holders of at least 25% in principal amount of the outstanding Convertible Notes by written notice to us and the Trustee, may declare 100% of the principal of and accrued and unpaid interest, if any, on all of the Convertible Notes to be due and payable. Upon such a declaration of acceleration, such principal and accrued and unpaid interest, if any, will be due and payable immediately. Upon the occurrence of certain events of bankruptcy, insolvency or reorganization involving us, 100% of the principal of and accrued and unpaid interest, if any, on all of the Convertible Notes will become due and payable automatically. Notwithstanding the foregoing, the indenture provides that, to the extent we elect and for up to 270 days, the sole remedy for an event of default relating to certain failures by us to comply with certain reporting covenants in the indenture consists exclusively of the right to receive additional interest on the Convertible Notes.
	In accordance with accounting guidance for debt with conversion and other options, we separately account for the liability and equity components of the Convertible Notes by allocating the proceeds between the liability component and the embedded conversion option, or equity component, due to our ability to settle the Convertible Notes in cash, common stock or a combination of cash and common stock, at our option. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The allocation was performed in a manner that reflected our non-convertible debt borrowing rate for similar debt. The equity component of the Convertible Notes was recognized as a debt discount and represents the difference between the proceeds from the issuance of the Convertible Notes and the fair value of the liability of the Convertible Notes on their respective dates of issuance. The excess of the principal amount of the liability component over its carrying amount, or debt discount, is amortized to interest expense using the effective interest method over five years, or the life of the Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification.
	Our outstanding convertible note balances as of March 31, 2014 consisted of the following:
		March 31, 2014
	Liability component:
	Principal	$	200,000
	Less: debt discount, net	(37,439		)
	Net carrying amount	$	162,561
	Equity component	$	38,188
	In connection with the issuance of the Convertible Notes, we incurred approximately $6.7 million of debt issuance costs, which primarily consisted of underwriting, legal and other professional fees, and allocated these costs to the liability and equity components based on the allocation of the proceeds. Of the total $6.7 million of debt issuance costs, $1.3 million were allocated to the equity component and recorded as a reduction to additional paid-in capital and $5.4 million were allocated to the liability component and recorded as assets on the balance sheet. The portion allocated to the liability component is amortized to interest expense over the expected life of the Convertible Notes using the effective interest method.
	We determined the expected life of the debt was equal to the five year term on the Convertible Notes. As of March 31, 2014, the carrying value of the Convertible Notes was $162.6 million and approximated their fair value due to the recent issuance of such Convertible Notes. The effective interest rate on the liability component was 7.23% for the period from the date of issuance through March 31, 2014. The following table sets forth total interest expense recognized related to the Convertible Notes during the three months ended March 31, 2014 (in thousands):
		March 31, 2014
	Contractual interest expense	$	625
	Amortization of debt issuance costs	102
	Amortization of debt discount	749
	Total interest expense	$	1,476
	Convertible Bond Hedge and Warrant Transactions
	In connection with the pricing of the Convertible Notes and in order to reduce the potential dilution to our common stock and/or offset cash payments due upon conversion of the Convertible Notes, on February 11, 2014 and February 13, 2014, we entered into convertible bond hedge transactions covering approximately 7.4 million shares of our common stock underlying the $200.0 million aggregate principal amount of the Convertible Notes, including the exercise of the over-allotment option, with JPMorgan Chase Bank, National Association, London Branch, Morgan Stanley & Co. International plc and Royal Bank of Canada, or together the Call Spread Counterparties. The convertible bond hedges have an exercise price of approximately $27.09 per share, subject to adjustment upon certain events, and are exercisable when and if the Convertible Notes are converted. If upon conversion of the Convertible Notes, the price of our common stock is above the exercise price of the convertible bond hedges, the Call Spread Counterparties will deliver shares of our common stock and/or cash with an aggregate value approximately equal to the difference between the price of our common stock at the conversion date and the exercise price, multiplied by the number of shares of our common stock related to the convertible bond hedges being exercised. The convertible bond hedges are separate transactions entered into by us and are not part of the terms of the Convertible Notes or the warrants, discussed below. Holders of the Convertible Notes will not have any rights with respect to the convertible bond hedges. We paid $39.8 million for these convertible bond hedges and recorded this amount as a reduction to additional paid-in capital, net of tax.
	At the same time, we also entered into separate warrant transactions with each of the Call Spread Counterparties relating to, in the aggregate, approximately 7.4 million shares of our common stock underlying the $200.0 million aggregate principal amount of the Convertible Notes, including the exercise of the over-allotment option. The initial exercise price of the warrants is $34.12 per share, subject to adjustment upon certain events, which is 70% above the last reported sale price of our common stock of $20.07 on February 11, 2014. The warrants would separately have a dilutive effect to the extent that the market value per share of our common stock, as measured under the terms of the warrants, exceeds the applicable exercise price of the warrants. The warrants were issued to the Call Spread Counterparties pursuant to the exemption from registration set forth in Section 4(a)(2) of the Securities Act. We received $25.7 million for these warrants and recorded this amount to additional paid-in capital.
	Aside from the initial payment of a $39.8 million premium to the Call Spread Counterparties under the convertible bond hedges, which amount is partially offset by the receipt of a $25.7 million premium under the warrants, we are not required to make any cash payments to the Call Spread Counterparties under the convertible bond hedges and will not receive any proceeds if the warrants are exercised.

Stockholders_Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2014
Stockholders' Equity	'
Stockholders' Equity	'
	Q.           Stockholders’ Equity
	In connection with the pricing of the Convertible Notes, on February 11, 2014, we and American Stock Transfer & Trust Company, LLC, or the Rights Agent, entered into an amendment, or the Amendment, to the Rights Agreement, dated as of September 4, 2009, between us and the Rights Agent. The Amendment, among other things, provides that, notwithstanding anything in the Rights Agreement to the contrary, each Call Spread Counterparty shall be deemed not to beneficially own any common shares underlying, or synthetically owned pursuant to, any Warrant held by such Call Spread Counterparty, any common shares held by such Call Spread Counterparty (or any affiliate thereof) to hedge its exposure with respect to the convertible bond hedges and warrants, any common shares underlying, or synthetically owned pursuant to, any Derivative Securities (as such term is defined in the Rights Agreement), including the Convertible Notes, held, or entered into, by such Call Spread Counterparty (or any affiliate thereof) to hedge its exposure with respect to the convertible bond hedges and warrants or any Convertible Notes held by such Call Spread Counterparty (or any affiliate thereof) in its capacity as underwriter in the notes offering.
	Total stockholders’ equity increased $18.7 million compared to December 31, 2013. This increase was primarily driven by $38.2 million allocated to the equity portion of our Convertible Notes, as described in Note P, “Debt,” and $1.9 million in stock-based compensation expense. These increases were partially offset by our net loss of $7.1 million, $14.1 million paid for the cost of the convertible bond hedges, net of the sale of warrants, and $1.3 million in debt issuance costs that were allocated to the equity component of the Convertible Notes, also described further in Note P.

Recently_Issued_and_Proposed_A

Recently Issued and Proposed Accounting Pronouncements	3 Months Ended
	Mar. 31, 2014
Recently Issued and Proposed Accounting Pronouncements	'
Recently Issued and Proposed Accounting Pronouncements	'
	R.                                    Recently Issued and Proposed Accounting Pronouncements
	From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board or other standard setting bodies that are adopted by us as of the specified effective date. Unless otherwise discussed, we believe that the impact of recently issued standards that are not yet effective will not have a material impact on our financial position or results of operations upon adoption.

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Basis of Presentation and Summary of Significant Accounting Policies	'
Use of Estimates and Assumptions	'
	Use of Estimates and Assumptions
	The preparation of condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities. The most significant estimates and assumptions are used in, but are not limited to, revenue recognition related to product sales and collaboration agreements, product sales allowances and accruals, assessing investments for potential other-than-temporary impairment, determining the fair values of our investments, assets acquired in a business combination, our debt obligations, and contingent consideration, the impairment of long-lived assets, including intangible assets, accrued expenses, and equity-based compensation expense. Actual results could differ materially from those estimates.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	Cash and cash equivalents consists principally of cash held in commercial bank accounts, money market funds and U.S. Treasury securities having an original maturity of less than three months. We consider all highly liquid investments with a maturity of three months or less at acquisition date to be cash equivalents. At March 31, 2014, substantially all of our cash and cash equivalents were held in either commercial bank accounts or money market funds.
Principles of Consolidation	'
	Principles of Consolidation
	The accompanying condensed consolidated financial statements include our accounts and the accounts of our wholly-owned subsidiaries, AMAG Europe Limited, AMAG Securities Corporation and Snowbird, Inc. AMAG Europe Limited was incorporated in October 2009 in London, England. AMAG Securities Corporation is a Massachusetts corporation which was incorporated in August 2007. Snowbird, Inc. is a Delaware corporation which was incorporated in December 2013. All intercompany account balances and transactions between the companies have been eliminated.
Fair Value Measurements	'
	Fair Value Measurements
	Under current accounting standards, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.
	Current accounting guidance establishes a hierarchy used to categorize how fair value is measured and which is based on three levels of inputs, of which the first two are considered observable and the third unobservable, as follows:
	Level 1 - Quoted prices in active markets for identical assets or liabilities.
	Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	We hold certain assets and liabilities that are required to be measured at fair value on a recurring basis, including our cash equivalents, investments, and contingent consideration.
Revenue Recognition and Related Sales Allowances and Accruals	'
	Revenue Recognition and Related Sales Allowances and Accruals
	An analysis of our U.S. Feraheme product sales allowances and accruals for the three months ended March 31, 2014 and 2013 is as follows (in thousands):
		Three Months Ended March 31,
		2014			2013
	Provision for U.S. Feraheme product sales allowances and accruals
	Discounts and chargebacks	$	10,533		$	7,493
	Government and other rebates	3,187			2,387
	Returns	226			193
	Total provision for U.S. Feraheme product sales allowances and accruals	$	13,946		$	10,073
	Total gross U.S. Feraheme product sales	$	31,321		$	25,651
	Total provision for U.S. Feraheme product sales allowances and  accruals as a percent of total gross U.S. Feraheme product sales	45		%	39		%
	Consistent with industry practice, we generally offer our wholesalers, specialty distributors and other customers a limited right to return Feraheme based on the product’s expiration date which, once packaged, is currently five years in the U.S. We estimate product returns based on the historical return patterns and known or expected changes in the marketplace. We currently have limited actual returns data, and therefore are not able to solely rely on our actual returns experience. We track actual returns by individual production lots. Returns on lots eligible for credits under our returned goods policy are monitored and compared with historical return trends and rates.
	We consider several additional factors in our product return estimation process, including our internal sales forecasts and inventory levels in the distribution channel. We expect that wholesalers and healthcare providers will not stock significant inventory due to the cost and expense to store Feraheme. Based on these factors, we determine whether an adjustment to the sales return reserve is appropriate.
	We record an estimate of returns at the time of sale. If necessary, our estimated rate of returns may be adjusted for actual return experience as it becomes available and for known or expected changes in the marketplace. We did not significantly adjust our reserve for product returns during the three months ended March 31, 2014 or 2013. To date, returns of Feraheme have been relatively limited and returns experience may change over time. A future adjustment to our product returns estimate would result in a corresponding change to our net product sales in the period of adjustment and could be significant.
	In addition, as part of our sales allowances and accruals, we reserve for estimated Medicaid rebates associated with instances where Medicaid will act as the insurer and for which we are required to pay a statutory rebate to Medicaid. We regularly assess our Medicaid reserve balance and the rate at which we accrue for claims against product sales. We did not adjust our Medicaid reserve balance during the three months ended March 31, 2014 or 2013. If we determine in future periods that our actual rebate experience is not indicative of expected claims, if our actual claims experience changes, or if other factors affect estimated claims rates, we may be required to adjust our current Medicaid accumulated reserve estimate, which would affect our net product sales in the period of the adjustment and could be significant.

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2014
Basis of Presentation and Summary of Significant Accounting Policies	'
Analysis of U.S. Feraheme product sales allowances and accruals	'
	An analysis of our U.S. Feraheme product sales allowances and accruals for the three months ended March 31, 2014 and 2013 is as follows (in thousands):
		Three Months Ended March 31,
		2014			2013
	Provision for U.S. Feraheme product sales allowances and accruals
	Discounts and chargebacks	$	10,533		$	7,493
	Government and other rebates	3,187			2,387
	Returns	226			193
	Total provision for U.S. Feraheme product sales allowances and accruals	$	13,946		$	10,073
	Total gross U.S. Feraheme product sales	$	31,321		$	25,651
	Total provision for U.S. Feraheme product sales allowances and  accruals as a percent of total gross U.S. Feraheme product sales	45		%	39		%
Schedule of customers representing 10% or more of revenues	'
		Three Months Ended March 31,
		2014		2013
	AmerisourceBergen Drug Corporation	39	%	43	%
	McKesson Corporation	22	%	22	%
	Cardinal Health, Inc.	15	%	15	%
	Takeda Pharmaceuticals Company Limited	11	%	12	%

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Investments	'
Summary of investments	'
	The following is a summary of our investments as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Corporate debt securities
	Due in one year or less	$	23,492	$	46	$	(2	)	$	23,536
	Due in one to three years	108,536		159		(47		)	108,648
	U.S. treasury and government agency securities
	Due in one year or less	21,079		35		—			21,114
	Due in one to three years	29,772		17		(28		)	29,761
	Commercial paper
	Due in one year or less	1,499		—		(1		)	1,498
	Total investments	$	184,378	$	257	$	(78	)	$	184,557
		December 31, 2013
				Gross		Gross			Estimated
		Amortized		Unrealized		Unrealized			Fair
		Cost		Gains		Losses			Value
	Corporate debt securities
	Due in one year or less	$	42,609	$	44	$	(4	)	$	42,649
	Due in one to three years	91,443		137		(106		)	91,474
	U.S. treasury and government agency securities
	Due in one year or less	18,526		19		—			18,545
	Due in one to three years	34,123		37		(25		)	34,135
	Total investments	$	186,701	$	237	$	(135	)	$	186,803

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Schedule of assets and liabilities measured at fair value on a recurring basis	'
	The following tables represent the fair value hierarchy as of March 31, 2014 and December 31, 2013 for those assets and liabilities that we measure at fair value on a recurring basis (in thousands):
		Fair Value Measurements at March 31, 2014 Using:
					Quoted Prices in Active		Significant Other		Significant
					Markets for Identical		Observable Inputs		Unobservable
					Assets				Inputs
		Total			(Level 1)		(Level 2)		(Level 3)
	Assets:
	Money market funds	$	196,297		$	196,297	$	—	$	—
	Corporate debt securities	132,184			$	—	132,184		—
	U.S. treasury and government agency securities	50,875			$	—	50,875		—
	Commercial paper	1,498			—		1,498		—
	Total Assets	$	380,854		$	196,297	$	184,557	$	—
	Liabilities:
	Acquisition-related contingent consideration	$	15,382		—		—		15,382
	Total Liabilities	$	15,382		$	—	$	—	$	15,382
		Fair Value Measurements at December 31, 2013 Using:
					Quoted Prices in Active		Significant Other		Significant
					Markets for Identical		Observable Inputs		Unobservable
					Assets				Inputs
		Total			(Level 1)		(Level 2)		(Level 3)
	Assets:
	Money market funds	$	18,767		$	18,767	$	—	$	—
	Corporate debt securities	134,123			—		134,123		—
	U.S. treasury and government agency securities	52,680			—		52,680		—
	Total Assets	$	205,570		$	18,767	$	186,803	$	—
	Liabilities:
	Acquisition-related contingent consideration	$	14,550		$	—	$	—	$	14,550
	Total Liabilities	$	14,550		$	—	$	—	$	14,550
Schedule of reconciliation of contingent consideration obligations related to acquisition of MuGard rights measured on recurring basis using Level 3 inputs	'
	The following table presents a reconciliation of contingent consideration obligations related to our acquisition of the MuGard Rights measured on a recurring basis using Level 3 inputs as of March 31, 2014 (in thousands):
	Balance as of December 31, 2013	$	14,550
	Payments made	(31		)
	Adjustments to fair value of contingent consideration	789
	Other adjustments	74
	Balance as of March 31, 2014	$	15,382

Accounts_Receivable_Net_Tables

Accounts Receivable, Net (Tables)	3 Months Ended
	Mar. 31, 2014
Accounts Receivable, Net	'
Schedule of customers representing greater than 10% of accounts receivable balances	'
		March 31, 2014		December 31, 2013
	AmerisourceBergen Drug Corporation	52	%	49	%
	McKesson Corporation	27	%	27	%
	Cardinal Health, Inc.	15	%	16	%

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventories	'
Schedule of major classes of inventories	'
	Our major classes of inventories were as follows as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014		December 31, 2013
	Raw materials	$	4,116	$	3,157
	Work in process	8,929		8,322
	Finished goods	7,759		5,738
	Total inventories	$	20,804	$	17,217

Property_and_Equipment_Net_Tab

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2014
Property and Equipment, Net	'
Schedule of property and equipment	'
	Property and equipment consisted of the following as of March 31, 2014 and December 31, 2013 (in thousands):
		March 31, 2014			December 31, 2013
	Furniture and fixtures	$	1,489		$	1,536
	Leasehold improvements	430			430
	Laboratory and production equipment	493			376
		2,412			2,342
	Less - accumulated depreciation	(575		)	(496		)
	Property and equipment, net	$	1,837		$	1,846

Business_Combination_Tables

Business Combination (Tables)	3 Months Ended
	Mar. 31, 2014
Business Combination	'
Summary of total consideration for the MuGard Rights	'
	The following table summarizes the total consideration for the MuGard Rights (in thousands):
	Consideration:
	Cash	$	3,434
	Acquisition-related contingent consideration	13,700
	Total consideration	$	17,134
Summary of estimated fair values of the assets acquired related to the business combination	'
	The following table summarizes the estimated fair values of the assets acquired related to the business combination as of the Acquisition Date (in thousands):
	Assets Acquired:
	MuGard intangible asset	$	16,893
	Inventory	241
	Net identifiable assets acquired	$	17,134

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Loss	'
Schedule of changes in accumulated other comprehensive loss, net of tax	'
	The changes in accumulated other comprehensive loss, net of tax, for the three months ended March 31, 2014 and 2013 consisted of the following (in thousands):
		Three Months Ended March 31,
		2014			2013
	Beginning Balance	$	(3,491	)	$	(3,247	)
	Other comprehensive income (loss) before reclassifications	77			(87		)
	Gain (loss) reclassified from other accumulated comprehensive loss	—			(6		)
	Ending Balance	$	(3,414	)	$	(3,340	)

Net_Loss_per_Share_Tables

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Net Loss per Share	'
Schedule of components of basic and diluted net loss per share	'
	The components of basic and diluted net loss per share were as follows (in thousands, except per share data):
		Three Months Ended March 31,
		2014			2013
	Net loss	$	(7,102	)	$	(3,895	)
	Weighted average common shares outstanding	21,824			21,544
	Net loss per share:
	Basic and diluted	$	(0.33	)	$	(0.18	)
Schedule of anti-dilutive securities excluded from computation of diluted net loss per share	'
	The following table sets forth the potential common shares issuable upon the exercise of outstanding options, the vesting of RSUs and warrants (prior to consideration of the treasury stock method), which were excluded from our computation of diluted net loss per share because such instruments were anti-dilutive (in thousands):
		Three Months Ended March 31,
		2014		2013
	Options to purchase shares of common stock	3,335		2,750
	Shares of common stock issuable upon the vesting of restricted stock units	481		510
	Warrants	7,382		—
	Total	11,198		3,260

EquityBased_Compensation_Table

Equity-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Equity-Based Compensation	'
Schedule of equity-based compensation expense	'
	Equity-based compensation expense for the three months ended March 31, 2014 and 2013, consisted of the following (in thousands):
		Three Months Ended March 31
		2014		2013
	Cost of product sales	$	28	$	23
	Research and development	449		932
	Selling, general and administrative	1,453		1,328
	Total equity-based compensation expense	$	1,930	$	2,283

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt	'
Schedule of outstanding convertible note balances	'
		March 31, 2014
	Liability component:
	Principal	$	200,000
	Less: debt discount, net	(37,439		)
	Net carrying amount	$	162,561
	Equity component	$	38,188
Schedule of total interest expense recognized related to the Convertible Notes	'
	The following table sets forth total interest expense recognized related to the Convertible Notes during the three months ended March 31, 2014 (in thousands):
		March 31, 2014
	Contractual interest expense	$	625
	Amortization of debt issuance costs	102
	Amortization of debt discount	749
	Total interest expense	$	1,476

Basis_of_Presentation_and_Summ3

Basis of Presentation and Summary of Significant Accounting Policies (Details ) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Provision for U.S. Feraheme product sales allowances and accruals	'	'
Discounts and chargebacks	$10,533	$7,493
Government and other rebates	3,187	2,387
Returns	226	193
Total provision for U.S. Feraheme product sales allowances and accruals	13,946	10,073
Total gross U.S. Feraheme product sales	$31,321	$25,651
Total provision for U.S. Feraheme product sales allowances and accruals as a percent of total gross U.S. Feraheme product sales	45.00%	39.00%
Current expiration period for packaged products	'5 years	'

Basis_of_Presentation_and_Summ4

Basis of Presentation and Summary of Significant Accounting Policies (Details 2) (USD $)

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2013

Dec. 31, 2012

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Mar. 31, 2013

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Sales Revenue, Net

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Revenue Concentration Risk

Geographical Concentration Risk

Geographical Concentration Risk

AmerisourceBergen Drug Corporation.

AmerisourceBergen Drug Corporation.

McKesson Corporation

McKesson Corporation

Cardinal Health, Inc

Cardinal Health, Inc

Takeda Pharmaceutical Company Limited (outside the U.S.)

Takeda Pharmaceutical Company Limited (outside the U.S.)

GPO

GPO

Investment Concentration Risk

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash, cash equivalents and investments

$385,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investment in institutional money market funds, and commercial paper

196,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash and cash equivalents

200,916,000

26,986,000

33,845,000

46,293,000

'

'

'

'

'

'

'

'

'

'

'

'

Amount invested in a single fund

$179,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Customers representing 10% or more of revenues

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of revenues from major customer

'

'

'

'

39.00%

43.00%

22.00%

22.00%

15.00%

15.00%

11.00%

12.00%

28.00%

30.00%

'

'

Percentage of revenues From customers outside of the U.S.

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Approximate percentage of revenues from customers outside the U.S.

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16.00%

12.00%

Investments_Details

Investments (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of Investments	'	'
Available-for-sale securities, Amortized Cost	$184,378	$186,701
Available-for-sale securities, Gross Unrealized Gains	257	237
Available-for-sale securities, Gross Unrealized Losses	-78	-135
Available-for-sale securities, Estimated Fair Value	184,557	186,803
Corporate debt securities	'	'
Summary of Investments	'	'
Available-for-sale securities due in one year or less, Amortized Cost	23,492	42,609
Available-for-sale securities due in one to three years, Amortized Cost	108,536	91,443
Available-for-sale securities due in one year or less, Gross Unrealized Gains	46	44
Available-for-sale securities due in one to three years, Gross Unrealized Gains	159	137
Available-for-sale securities due in one year or less, Gross Unrealized Losses	-2	-4
Available-for-sale securities due in one to three years, Gross Unrealized Losses	-47	-106
Available-for-sale securities due in one year or less, Estimated Fair Value	23,536	42,649
Available-for-sale securities due in one to three years, Estimated Fair Value	108,648	91,474
U.S. treasury and government agency securities	'	'
Summary of Investments	'	'
Available-for-sale securities due in one year or less, Amortized Cost	21,079	18,526
Available-for-sale securities due in one to three years, Amortized Cost	29,772	34,123
Available-for-sale securities due in one year or less, Gross Unrealized Gains	35	19
Available-for-sale securities due in one to three years, Gross Unrealized Gains	17	37
Available-for-sale securities due in one to three years, Gross Unrealized Losses	-28	-25
Available-for-sale securities due in one year or less, Estimated Fair Value	21,114	18,545
Available-for-sale securities due in one to three years, Estimated Fair Value	29,761	34,135
Commercial paper	'	'
Summary of Investments	'	'
Available-for-sale securities due in one year or less, Amortized Cost	1,499	'
Available-for-sale securities due in one year or less, Gross Unrealized Losses	-1	'
Available-for-sale securities due in one year or less, Estimated Fair Value	$1,498	'

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (Recurring basis, USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair value of assets and liabilities measured on a recurring basis	'	'
Transfers or reclassifications of securities from Level 1 to Level 2	$0	'
Transfers or reclassifications of securities from Level 2 to Level 1	0	'
Total	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	380,854	205,570
Total Liabilities	15,382	14,550
Total | Acquisition-related contingent consideration	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Liabilities	15,382	14,550
Total | Money market funds	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	196,297	18,767
Total | Corporate debt securities	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	132,184	134,123
Total | U.S. treasury and government agency securities	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	50,875	52,680
Total | Commercial paper	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	1,498	'
Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	196,297	18,767
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	196,297	18,767
Significant Other Observable Inputs (Level 2)	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	184,557	186,803
Significant Other Observable Inputs (Level 2) | Corporate debt securities	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	132,184	134,123
Significant Other Observable Inputs (Level 2) | U.S. treasury and government agency securities	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	50,875	52,680
Significant Other Observable Inputs (Level 2) | Commercial paper	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Assets	1,498	'
Significant Unobservable Inputs (Level 3)	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Liabilities	15,382	14,550
Significant Unobservable Inputs (Level 3) | Acquisition-related contingent consideration	'	'
Fair value of assets and liabilities measured on a recurring basis	'	'
Total Liabilities	$15,382	$14,550

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	3 Months Ended				3 Months Ended		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Feb. 28, 2014	Feb. 14, 2014	Mar. 31, 2014	Jun. 06, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
		Notes	Notes	Notes	Access	Access	Access	Access	Access
					MuGard Rights	MuGard Rights	MuGard Rights	MuGard Rights	MuGard Rights
							Recurring basis	Minimum	Maximum
							Significant Unobservable Inputs (Level 3)
Reconciliation of contingent consideration obligations related to acquisition of MuGard rights	'	'	'	'	'	'	'	'	'
Balance at beginning of period	'	'	'	'	$14,550,000	'	'	'	'
Payments made	'	'	'	'	-31,000	'	'	'	'
Adjustments to fair value of contingent consideration	789,000	'	'	'	789,000	'	'	'	'
Other adjustments	'	'	'	'	74,000	'	'	'	'
Balance at end of period	'	'	'	'	15,382,000	'	'	'	'
Fair value of the contingent consideration	'	'	'	'	'	13,700,000	'	'	'
Estimated undiscounted royalty amounts payable	'	'	'	'	'	'	'	28,000,000	34,000,000
Period over which estimated undiscounted royalty amounts could be paid	'	'	'	'	'10 years	'	'	'	'
Discount rate (as a percent)	'	'	'	'	'	'	15.00%	'	'
Contingent consideration classified as short-term liability	'	'	'	'	1,300,000	'	'	'	'
Aggregate principal amount of notes issued	'	'	200,000,000	200,000,000	'	'	'	'	'
Interest rate (as a percent)	2.50%	2.50%	'	'	'	'	'	'	'
Estimated fair value of the Notes	'	$161,800,000	'	'	'	'	'	'	'

Accounts_Receivable_Net_Detail

Accounts Receivable, Net (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts Receivable, Net	'	'
Net Accounts receivable	10,115	6,842
Accounts Receivable. | Accounts receivable balances | AmerisourceBergen Drug Corporation.	'	'
Customers representing greater than 10% of accounts receivable balances	'	'
Accounts receivable by major customer (as a percent)	52.00%	49.00%
Accounts Receivable. | Accounts receivable balances | McKesson Corporation	'	'
Customers representing greater than 10% of accounts receivable balances	'	'
Accounts receivable by major customer (as a percent)	27.00%	27.00%
Accounts Receivable. | Accounts receivable balances | Cardinal Health, Inc	'	'
Customers representing greater than 10% of accounts receivable balances	'	'
Accounts receivable by major customer (as a percent)	15.00%	16.00%

Inventories_Details

Inventories (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Inventories	'	'	'
Raw materials	$4,116	$3,157	'
Work in process	8,929	8,322	'
Finished goods	7,759	5,738	'
Total inventories	20,804	17,217	11,292
Inventories disclosure	'	'	'
Inventory expensed	1,437	'	'
Cost of goods sold	'	'	'
Inventories disclosure	'	'	'
Inventory expensed	300	'	'
Research and development expenses	'	'	'
Inventories disclosure	'	'	'
Inventory expensed	$1,100	'	'

Property_and_Equipment_Net_Det

Property and Equipment, Net (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property and Equipment	'	'
Property and Equipment, gross	$2,412	$2,342
Less - accumulated depreciation	-575	-496
Property and equipment, net	1,837	1,846
Furniture and fixtures	'	'
Property and Equipment	'	'
Property and Equipment, gross	1,489	1,536
Leasehold improvements	'	'
Property and Equipment	'	'
Property and Equipment, gross	430	430
Laboratory and production equipment	'	'
Property and Equipment	'	'
Property and Equipment, gross	$493	$376

Business_Combination_Details

Business Combination (Details) (MuGard Rights, USD $)	Mar. 31, 2014	Jun. 06, 2013	Jun. 06, 2013	Jun. 30, 2013	Jun. 30, 2013
			Access	Access	Access
Business Combination	'	'	'	'	'
Upfront payment in consideration of license	'	'	'	$3,300,000	'
Consideration:	'	'	'	'	'
Cash	'	'	3,434,000	'	'
Acquisition-related contingent consideration	'	'	13,700,000	'	'
Total consideration	'	'	17,134,000	'	'
Assets Acquired	'	'	'	'	'
Acquired finite-lived intangible assets	16,800,000	16,900,000	16,893,000	'	'
Inventory	'	'	241,000	'	'
Net identifiable assets acquired	'	'	17,134,000	'	'
Acquisition-related costs	'	'	'	'	$800,000

Intangible_Assets_Net_Details

Intangible Assets, Net (Details) (MuGard Rights, USD $)	0 Months Ended		3 Months Ended
	Jun. 06, 2013	Mar. 31, 2014	Mar. 31, 2014
			Maximum
Intangible Assets, Net	'	'	'
Acquired finite-lived intangible assets	$16,900,000	$16,800,000	'
Useful life	'10 years	'	'
Amortization of MuGard intangible asset	'	'	$100,000

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Changes in accumulated other comprehensive income, net of tax	'	'
Beginning Balance	($3,491)	($3,247)
Other comprehensive income (loss) before reclassifications	77	-87
Gain (loss) reclassified from other accumulated comprehensive loss	'	-6
Ending Balance	($3,414)	($3,340)

Net_Loss_per_Share_Details

Net Loss per Share (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Components of basic and diluted net loss per share	'	'
Net loss	($7,102)	($3,895)
Weighted average common shares outstanding	21,824	21,544
Net loss per share:	'	'
Basic and diluted (in dollars per share)	($0.33)	($0.18)
Anti-dilutive securities excluded from the computation of diluted net loss per share	'	'
Anti-dilutive securities (in shares)	11,198	3,260
Stock options	'	'
Anti-dilutive securities excluded from the computation of diluted net loss per share	'	'
Anti-dilutive securities (in shares)	3,335	2,750
Shares of common stock issuable upon the vesting of restricted stock units	'	'
Anti-dilutive securities excluded from the computation of diluted net loss per share	'	'
Anti-dilutive securities (in shares)	481	510
Warrants	'	'
Anti-dilutive securities excluded from the computation of diluted net loss per share	'	'
Anti-dilutive securities (in shares)	7,382	'

EquityBased_Compensation_Detai

Equity-Based Compensation (Details)	1 Months Ended			3 Months Ended
	31-May-13	31-May-10	31-May-09	Mar. 31, 2014
Equity-Based Compensation	'	'	'	'
Number of equity compensation plans	'	'	'	2
2007 Equity Incentive Plan	'	'	'	'
Equity compensation plans	'	'	'	'
Shares authorized for issuance	1,100,000	800,000	600,000	'
Number of options and restricted stock units granted since inception (in shares)	'	'	'	7,076,175
Number of stock options expired or terminated since inception (in shares)	'	'	'	2,712,957
Number of restricted stock units forfeited since inception (in shares)	'	'	'	661,811
Stock options exercised since inception (in shares)	'	'	'	210,524
Shares of common stock issued pursuant to vested restricted stock units since inception	'	'	'	500,871
Number of stock options outstanding (in shares)	'	'	'	2,684,438
Number of restricted stock units outstanding (in shares)	'	'	'	305,574
Remaining number of shares available for future grants	'	'	'	1,514,760
2007 Equity Incentive Plan | Stock options | Minimum	'	'	'	'
Equity compensation plans	'	'	'	'
Expiration term	'	'	'	'7 years
2007 Equity Incentive Plan | Stock options | Maximum	'	'	'	'
Equity compensation plans	'	'	'	'
Expiration term	'	'	'	'10 years
2000 Stock Plan	'	'	'	'
Equity compensation plans	'	'	'	'
Number of options and restricted stock units granted since inception (in shares)	'	'	'	2,182,700
Number of stock options expired or terminated since inception (in shares)	'	'	'	984,339
Number of restricted stock units forfeited since inception (in shares)	'	'	'	1,500
Stock options exercised since inception (in shares)	'	'	'	1,052,045
Shares of common stock issued pursuant to vested restricted stock units since inception	'	'	'	42,500
Number of stock options outstanding (in shares)	'	'	'	102,316
Number of restricted stock units outstanding (in shares)	'	'	'	0
Remaining number of shares available for future grants	'	'	'	0
2000 Stock Plan | Stock options	'	'	'	'
Equity compensation plans	'	'	'	'
Expiration term	'	'	'	'10 years
Other Equity Compensation Grants | Stock options | Senior management	'	'	'	'
Equity compensation plans	'	'	'	'
Granted (in shares)	'	'	'	90,000
Award vesting period	'	'	'	'4 years
Other Equity Compensation Grants | RSUs | Senior management	'	'	'	'
Equity compensation plans	'	'	'	'
Granted (in shares)	'	'	'	35,000
Award vesting period	'	'	'	'4 years

EquityBased_Compensation_Detai1

Equity-Based Compensation (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Equity-based compensation expense	'	'
Total equity-based compensation expense	$1,930	$2,283
Cost of product sales	'	'
Equity-based compensation expense	'	'
Total equity-based compensation expense	28	23
Research and development	'	'
Equity-based compensation expense	'	'
Total equity-based compensation expense	449	932
Selling, general and administrative	'	'
Equity-based compensation expense	'	'
Total equity-based compensation expense	$1,453	$1,328

Commitments_and_Contingencies_

Commitments and Contingencies (Details)	3 Months Ended
	Mar. 31, 2014
Minimum	'
Patent appeals and market exclusivity	'
Estimated term to defend the validity of patent through the appeals process	'2 years
Ferumoxytol term of data and market exclusivity even if there is no successful outcome from the appeals process	'8 years
Maximum	'
Patent appeals and market exclusivity	'
Estimated term to defend the validity of patent through the appeals process	'3 years
Ferumoxytol term of data and market exclusivity even if there is no successful outcome from the appeals process	'10 years

Collaborative_Agreements_Detai

Collaborative Agreements (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Apr. 30, 2010	Mar. 31, 2010	Mar. 31, 2014	Dec. 31, 2010	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2008
			Takeda	Takeda	Takeda	Takeda	Takeda	Takeda	3SBio License Agreement	3SBio License Agreement
							Maximum	Maximum
Collaborative Agreements	'	'	'	'	'	'	'	'	'	'
Upfront payment received	'	'	$60,000,000	'	'	'	'	'	'	$1,000,000
Additional upfront payment	'	'	'	'	'	1,000,000	'	'	'	'
Period of recognition of deferred revenues	'	'	'	'10 years	'	'	'	'	'	'
Milestone payments expected to be received under the agreement	'	'	'	'	'	'	'	186,000,000	'	'
Deferred revenue recognized in earnings related to upfront payments	'	'	'	'	2,000,000	'	'	'	1,000,000	'
Other reimbursement revenues	'	'	'	'	100,000	'	100,000	'	'	'
Product sales and royalty revenue recognized	'	'	'	'	200,000	'	'	'	'	'
Deferred revenues	'	'	'	'	2,300,000	'	'	'	'	'
Deferred revenues, short-term	9,118,000	8,226,000	'	'	1,200,000	'	'	'	'	'
Deferred revenues, long-term	40,567,000	44,534,000	'	'	1,100,000	'	'	'	'	'
Deferred costs	'	'	'	'	2,200,000	'	'	'	'	'
Deferred costs, short-term	'	'	'	'	1,100,000	'	'	'	'	'
Deferred costs, long-term	'	'	'	'	$1,100,000	'	'	'	'	'

Debt_Details

Debt (Details) (USD $)

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

3 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Feb. 13, 2014

Feb. 11, 2014

Mar. 31, 2014

Feb. 28, 2014

Feb. 14, 2014

Mar. 31, 2014

Feb. 28, 2014

Feb. 11, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Conversion covenant under circumstance one

Conversion covenant under circumstance two

Conversion covenant under circumstance two

Conversion covenant under circumstance three

D

Maximum

Liability component:

'

'

'

'

'

'

'

'

'

'

'

'

Principal

'

'

$200,000,000

'

'

'

'

'

'

'

'

'

Less: debt discount, net

'

'

-37,439,000

'

'

'

'

'

'

'

'

'

Net carrying amount

'

'

162,561,000

'

'

162,600,000

'

'

'

'

'

'

Equity component

'

'

38,188,000

'

'

'

'

'

'

'

'

'

Aggregate principal amount of notes issued

'

'

'

'

200,000,000

'

200,000,000

'

'

'

'

'

Amount pertaining to full exercise of over-allotment of debt by underwriters

'

'

'

'

25,000,000

'

'

'

'

'

'

'

Proceeds from issuance of convertible debt

'

'

200,000,000

'

193,300,000

'

'

'

'

'

'

'

Fees and expenses

'

'

'

'

6,700,000

'

'

'

'

'

'

'

Proceeds used to pay the cost of the bond hedges (after such cost was partially offset by proceeds from the sale of warrants)

'

'

14,100,000

'

14,100,000

'

'

'

'

'

'

'

Interest rate (as a percent)

'

'

2.50%

'

'

2.50%

'

'

'

'

'

'

Initial conversion rate of common stock per $1000 of principal amount of Notes (in shares)

'

'

'

'

'

36.9079

'

'

'

'

'

'

Principal amount used for debt instrument conversion ratio

'

'

'

'

'

1,000

'

'

'

1,000

'

1,000

Initial conversion price of convertible notes into common stock (in dollars per share)

'

'

'

'

'

$27.09

'

'

'

'

'

'

Conversion premium (as a percent)

'

'

'

'

'

35.00%

'

'

'

'

'

'

Sale price of common stock (in dollars per share)

'

'

'

'

'

'

'

$20.07

'

'

'

'

Number of days during 30 consecutive trading days in which the closing price of the entity's common stock must exceed or equal the conversion price for the notes to be convertible

'

'

'

'

'

'

'

'

20

'

'

'

Number of consecutive trading days during which the closing price of the entity's common stock must exceed or equal the conversion price for at least 20 days in order for the notes to be convertible

'

'

'

'

'

'

'

'

'30 days

'

'

'

Percentage of the closing sales price of the entity's common stock that the conversion price must exceed or be equal in order for the notes to be convertible

'

'

'

'

'

'

'

'

130.00%

'

'

'

Number of consecutive business days after any five consecutive trading day period during the note measurement period

'

'

'

'

'

'

'

'

'

'5 days

'

'

Number of consecutive trading days before five consecutive business days during the note measurement period

'

'

'

'

'

'

'

'

'

'5 days

'

'

Percentage of product of the last reported sale price of the entity's common stock and the conversion rate of convertible debt instruments

'

'

'

'

'

'

'

'

'

'

98.00%

'

Repurchase price as a percentage of principal amount of notes plus accrued and unpaid interest

'

'

'

'

'

100.00%

'

'

'

'

'

'

Minimum percentage of principal amount held by holders to declare notes due and payable

'

'

'

'

'

25.00%

'

'

'

'

'

'

Percentage of principal amount due and payable in an event of default

'

'

'

'

'

100.00%

'

'

'

'

'

'

Percentage of principal amount due and payable in the event of default, arising out of certain events of bankruptcy, insolvency or reorganization

'

'

'

'

'

100.00%

'

'

'

'

'

'

Maximum period to comply any remedy for specified event of default relating to certain failures

'

'

'

'

'

'270 days

'

'

'

'

'

'

Debt issuance costs allocated to equity component

'

'

1,300,000

'

1,300,000

'

'

'

'

'

'

'

Debt issuance costs allocated to the liability component

'

'

'

'

5,400,000

'

'

'

'

'

'

'

Expected life of the debt

'

'

'

'

'

'5 years

'

'

'

'

'

'

Effective interest rate on liability component (as a percent)

'

'

'

'

'

7.23%

'

'

'

'

'

'

Total interest expense recognized

'

'

'

'

'

'

'

'

'

'

'

'

Contractual interest expense

'

'

'

'

'

625,000

'

'

'

'

'

'

Amortization of debt issuance costs

'

'

'

'

'

102,000

'

'

'

'

'

'

Amortization of debt discount

'

'

'

'

'

749,000

'

'

'

'

'

'

Total interest expense

'

'

1,476,000

'

'

1,476,000

'

'

'

'

'

'

Convertible Bond Hedge

'

'

'

'

'

'

'

'

'

'

'

'

Common stock covered under convertible bond hedge (in shares)

7.4

7.4

'

'

'

'

'

'

'

'

'

'

Exercise price (in dollars per unit)

$27.09

$27.09

'

'

'

'

'

'

'

'

'

'

Purchase of convertible bond hedge

'

'

39,760,000

'

'

'

'

'

'

'

'

'

Warrant Transactions

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares of common stock called by warrants

'

'

'

7.4

'

'

'

'

'

'

'

'

Exercise price (in dollars per share)

'

'

'

$34.12

'

'

'

'

'

'

'

'

Exercise price above last reported sale price of common stock (as a percent)

'

'

'

70.00%

'

'

'

'

'

'

'

'

Amount received on warrants sold

'

'

$25,620,000

'

'

'

'

'

'

'

'

'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stockholders' Equity	'	'
Increase in total stockholders' equity	$18,700,000	'
Increase in total stockholders' equity allocated to equity portion of Convertible Notes	38,188,000	'
Increase in total stockholders' equity allocated to stock-based compensation expense	1,930,000	2,283,000
Increase in total stockholders' equity partially offset by net loss	7,102,000	3,895,000
Increase in total stockholders' equity partially offset by paying for the cost of the convertible bond hedges, net of the sale of warrants	14,100,000	'
Increase in total stockholders' equity partially offset by debt issuance costs allocated to equity component of the Convertible Notes	$1,300,000	'