Amicus Therapeutics (FOLD) 10-Q 12 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 31, 2013
Document and Entity Information	'	'
Entity Registrant Name	'AMICUS THERAPEUTICS INC	'
Entity Central Index Key	'0001178879	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	49,631,672
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$30,047	$33,971
Investments in marketable securities	30,448	65,151
Receivable due from GSK	2,121	3,225
Prepaid expenses and other current assets	1,692	2,270
Total current assets	64,308	104,617
Property and equipment, less accumulated depreciation and amortization of $8,501 and $9,751 at December 31, 2012 and September 30, 2013, respectively	4,356	5,029
Other non-current assets	442	442
Total Assets	69,106	110,088
Current liabilities:	'	'
Accounts payable and accrued expenses	8,166	8,845
Current portion of secured loan	398	398
Warrant liability	34	'
Total current liabilities	8,598	9,243
Deferred reimbursements	34,019	30,418
Warrant liability, non-current	'	908
Secured loan, less current portion	'	299
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Common stock, $.01 par value, 125,000,000 shares authorized, 49,631,672 shares issued and outstanding at December 31, 2012, 125,000,000 shares authorized, 49,631,672 shares issued and outstanding at September 30, 2013	556	556
Additional paid-in capital	392,213	387,539
Accumulated other comprehensive income	5	14
Deficit accumulated during the development stage	-366,285	-318,889
Total stockholders' equity	26,489	69,220
Total Liabilities and Stockholders' Equity	$69,106	$110,088

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Consolidated Balance Sheets	'	'
Accumulated depreciation and amortization of property and equipment (in dollars)	$9,751	$8,501
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	49,631,672	49,631,672
Common stock, shares outstanding	49,631,672	49,631,672

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended		140 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Revenue:	'	'	'	'	'
Research revenue	$39	'	$39	$11,591	$57,532
Collaboration and milestone revenue	'	'	'	6,820	64,382
Total revenue	39	'	39	18,411	121,914
Operating Expenses:	'	'	'	'	'
Research and development	10,110	11,499	32,824	39,226	348,717
General and administrative	4,635	4,995	14,288	14,909	146,901
Restructuring charges	'	'	'	'	1,522
Impairment of leasehold improvements	'	'	'	'	1,030
Depreciation and amortization	429	422	1,318	1,284	13,086
In-process research and development	'	'	'	'	418
Total operating expenses	15,174	16,916	48,430	55,419	511,674
Loss from operations	-15,135	-16,916	-48,391	-37,008	-389,760
Other income (expenses):	'	'	'	'	'
Interest income	36	92	147	235	14,536
Interest expense	-7	-19	-26	-77	-2,448
Change in fair value of warrant liability	517	553	874	-1,941	2,427
Other income	'	'	'	21	252
Loss before tax benefit	-14,589	-16,290	-47,396	-38,770	-374,993
Income tax benefit	'	'	'	'	8,708
Net loss	-14,589	-16,290	-47,396	-38,770	-366,285
Deemed dividend	'	'	'	'	-19,424
Preferred stock accretion	'	'	'	'	-802
Net loss attributable to common stockholders	($14,589)	($16,290)	($47,396)	($38,770)	($386,511)
Net loss attributable to common stockholders per common shares - basic and diluted (in dollars per share)	($0.29)	($0.34)	($0.96)	($0.88)	'
Weighted-average common shares outstanding - basic and diluted (in shares)	49,621,188	48,513,647	49,621,188	44,255,885	'

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended		9 Months Ended		140 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Consolidated Statements of Comprehensive Loss	'	'	'	'	'
Net loss	($14,589,000)	($16,290,000)	($47,396,000)	($38,770,000)	($366,285,000)
Other comprehensive (loss)/ income:	'	'	'	'	'
Unrealized gain/ (loss) on available-for-sale securities	2,000	20,000	-9,000	33,000	5,000
Other comprehensive income / (loss), before income taxes	2,000	20,000	-9,000	33,000	5,000
Other comprehensive income/ (loss)	2,000	20,000	-9,000	33,000	5,000
Comprehensive loss	($14,587,000)	($16,270,000)	($47,405,000)	($38,737,000)	($366,280,000)

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended		140 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Operating activities	'	'	'
Net loss	($47,396)	($38,770)	($366,285)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'	'
Non-cash interest expense	'	'	525
Depreciation and amortization	1,318	1,284	13,086
Amortization of non-cash compensation	'	'	522
Stock-based compensation - employees	4,674	4,743	46,603
Stock-based compensation - non-employees	'	'	853
Stock-based license payments	'	'	1,220
Change in fair value of warrant liability	-874	1,941	-2,427
Loss on disposal of asset	'	28	388
Impairment of leasehold improvements	'	'	1,030
Non-cash charge for in-process research and development	'	'	418
Beneficial conversion feature related to bridge financing	'	'	135
Changes in operating assets and liabilities:	'	'	'
Receivable due from GSK	1,104	1,859	-2,121
Prepaid expenses and other current assets	578	2,826	-1,692
Other non-current assets	'	267	-466
Accounts payable and accrued expenses	-679	-280	8,166
Deferred reimbursements	3,601	-268	34,019
Net cash used in operating activities	-37,674	-26,370	-266,026
Investing activities	'	'	'
Redemption of marketable securities	68,348	47,445	823,790
Purchases of marketable securities	-33,654	-99,320	-854,349
Purchases of property and equipment	-645	-4,167	-18,858
Net cash (used in)/ provided by investing activities	34,049	-56,042	-49,417
Financing activities	'	'	'
Proceeds from the issuance of preferred stock, net of issuance costs	'	'	143,022
Proceeds from the issuance of common stock and warrants, net of issuance costs	'	80,195	193,441
Proceeds from the issuance of convertible notes	'	'	5,000
Payments of capital lease obligations	'	'	-5,587
Payments of secured loan agreement	-299	-1,139	-4,355
Proceeds from exercise of stock options	'	966	3,341
Proceeds from exercise of warrants (common and preferred)	'	'	264
Proceeds from capital asset financing arrangement	'	'	5,611
Proceeds from secured loan arrangement	'	995	4,753
Net cash provided by/ (used in) financing activities	-299	81,017	345,490
Net (decrease)/ increase in cash and cash equivalents	-3,924	-1,395	30,047
Cash and cash equivalents at beginning of period	33,971	25,668	'
Cash and cash equivalents at end of period	30,047	24,273	30,047
Supplemental disclosures of cash flow information	'	'	'
Cash paid during the period for interest	24	72	2,141
Non-cash activities	'	'	'
Conversion of warrants to common stock	'	'	386
Conversion of notes payable to Series B redeemable convertible preferred stock	'	'	5,000
Conversion of preferred stock to common stock	'	'	148,951
Accretion of redeemable convertible preferred stock	'	'	802
Beneficial conversion feature related to the issuance of Series C redeemable convertible preferred stock	'	'	$19,424

Description_of_Business_and_Si

Description of Business and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Description of Business and Significant Accounting Policies	'
Description of Business and Significant Accounting Policies	'
	Note 1.   Description of Business and Significant Accounting Policies
	Corporate Information, Status of Operations and Management Plans
	Amicus Therapeutics, Inc. (“we,” “us,” “our,” “Amicus” or the “Company”) was incorporated on February 4, 2002 in Delaware and is a biopharmaceutical company focused on the discovery, development and commercialization of next-generation medicines for a range of rare and orphan diseases, with a focus on improved therapies for lysosomal storage diseases (“LSDs”). The Company’s lead program is migalastat HCl for Fabry disease.  Migalastat HCl is a novel, small molecule pharmacological chaperone in development as a monotherapy and in combination with ERT for Fabry disease.  The Company is leveraging its Chaperone-Advanced Replacement Therapy, or CHART™  platform to develop next-generation therapies that combine pharmacological chaperones with enzyme therapies for Pompe, Mucopolysaccharidosis Type I (“MPS I”) and Gaucher diseases.  Current CHART™ programs for Pompe disease include the pharmacological chaperone AT2220 (duvoglustat HCl) co-administered with currently marketed Pompe ERTs (Myozyme®/Lumizyme®), as well as AT2220 co-formulated with a proprietary Pompe ERT. The Company’s activities since inception have consisted principally of raising capital, establishing facilities, and performing research and development. Accordingly, the Company is considered to be in the development stage.
	On September 10, 2013, the Company entered into a collaboration agreement with Biogen Idec (“Biogen”) to discover, develop and commercialize novel small molecules for the treatment of Parkinson’s disease. The collaboration will build upon preclinical studies at the Company and independent published research that suggest increasing activity of the lysosomal enzyme glucocerobrosidase (“GCase”) in the brain may correct alpha-synuclein pathology and other deficits associated with Parkinson’s disease. Under terms of the multi-year agreement, the Company and Biogen will collaborate in the discovery of a new class of small molecules that target the GCase enzyme, for further development and commercialization by Biogen. Biogen will be responsible for funding all discovery, development, and commercialization activities. In addition the Company will be reimbursed for all full-time employees working on the project. The Company is also eligible to receive development and regulatory milestones, as well as modest royalties on global net sales.
	On July 17, 2012, the Company entered into an Amended and Restated License and Expanded Collaboration Agreement (the “Expanded Collaboration Agreement”) with an affiliate of GSK pursuant to which the Company and GSK continue to develop and commercialize migalastat HCl for the treatment of Fabry disease. The Expanded Collaboration Agreement amends and replaces in its entirety the License and Collaboration Agreement entered into between the Company and GSK on October 28, 2010 (the “Original Collaboration Agreement”) for the development and commercialization of migalastat HCl. Under the terms of the Expanded Collaboration Agreement, the Company and GSK are co-developing all formulations of migalastat HCl for Fabry disease, including migalastat HCl monotherapy, currently in Phase 3 development, as well as migalastat HCl co-formulated with an investigational ERT for Fabry disease (the “Co-formulated Product”). The Co-formulated Product is being developed by the Company and GSK in collaboration with JCR Pharmaceutical Co. Ltd. The Company will commercialize all migalastat HCl products for Fabry disease in the United States while GSK will commercialize all such products in the rest of the world.
	The Company and GSK jointly fund development costs for all formulations of migalastat HCl in accordance with agreed upon development plans pursuant to which the Company and GSK fund 40% and 60% of such costs, respectively, for 2013 and through the end of the development plans.  Additionally, simultaneous with entry into the Expanded Collaboration Agreement, the Company and GSK entered into a Stock Purchase Agreement (the “SPA”) pursuant to which GSK purchased approximately 2.9 million shares of the Company’s common stock at a price of $6.30 per share. The total value of this equity investment to the Company is approximately $18.6 million. As of September 30, 2013, GSK’s ownership position in the Company is approximately19.8%.
	For further information, see “— Note 7. Collaborative Agreements”
	The Company had an accumulated deficit of approximately $366.3 million at September 30, 2013 and anticipates incurring losses through the fiscal year ending December 31, 2013 and beyond. The Company has not yet generated commercial sales revenue and has been able to fund its operating losses to date through the sale of its redeemable convertible preferred stock, issuance of convertible notes, net proceeds from its initial public offering (“IPO”) and subsequent stock offerings, payments from partners during the terms of the collaboration agreements and other financing arrangements. In March 2010, the Company sold 4.95 million shares of its common stock and also sold warrants to purchase 1.9 million shares of common stock in a registered direct offering to a select group of institutional investors for net proceeds of $17.1 million. In October 2010, the Company sold 6.87 million shares of its common stock as part of the Original Collaboration Agreement with GSK for proceeds of $31.0 million. In March 2012, the Company sold 11.5 million shares of its common stock in a stock offering for net proceeds of $62.0 million. In July 2012, the Company sold 2.9 million shares of its common stock as part of the Expanded Collaboration Agreement with GSK for proceeds of $18.6 million. The Company believes that its existing cash and cash equivalents and short-term investments will be sufficient to cover its cash flow requirements into the fourth quarter of 2014.
	Basis of Presentation
	The Company has prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X.  Accordingly, the unaudited consolidated financial statements do not include all of the information and disclosures required by U.S. GAAP for complete financial statements.  In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information.
	The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the Company’s financial statements and related notes as contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012.  For a complete description of the Company’s accounting policies, please refer to the Annual Report on Form 10-K for the fiscal year ended December 31, 2012.
	Revenue Recognition
	The Company recognizes revenue when amounts are realized or realizable and earned.  Revenue is considered realizable and earned when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred or services have been rendered; (3) the price is fixed or determinable; and (4) collection of the amounts due are reasonably assured.
	In multiple element arrangements, revenue is allocated to each separate unit of accounting and each deliverable in an arrangement is evaluated to determine whether it represents separate units of accounting. A deliverable constitutes a separate unit of accounting when it has standalone value and there is no general right of return for the delivered elements. In instances when the aforementioned criteria are not met, the deliverable is combined with the undelivered elements and the allocation of the arrangement consideration and revenue recognition is determined for the combined unit as a single unit of accounting. Allocation of the consideration is determined at arrangement inception on the basis of each unit’s relative selling price.  In instances where there is determined to be a single unit of accounting, the total consideration is applied as revenue for the single unit of accounting and is recognized over the period of inception through the date when the last deliverable within the single unit of accounting is expected to be delivered.
	The Company’s current revenue recognition policies, which were adopted and first applied in fiscal 2010, provide that, when a collaboration arrangement contains multiple deliverables, such as license and research and development services, the Company allocates revenue to each separate unit of accounting based on a selling price hierarchy. The selling price hierarchy for a deliverable is based on (i) its vendor specific objective evidence (“VSOE”) if available, (ii) third party evidence (“TPE”) if VSOE is not available, or (iii) best estimated selling price (“BESP”) if neither VSOE nor TPE is available. The Company would establish the VSOE of selling price using the price charged for a deliverable when sold separately. The TPE of selling price would be established by evaluating largely similar and interchangeable competitor products or services in standalone sales to similarly situated customers. The BESP would be established considering internal factors such as an internal pricing analysis or an income approach using a discounted cash flow model.
	The Company also considers the impact of potential future payments it makes in its role as a vendor to its customers and evaluates if these potential future payments could be a reduction of revenue from that customer. If the potential future payments to the customer are as follows:
	·                  a payment for an identifiable benefit; and
	·                  the identifiable benefit is separable from the existing relationship between the Company and its customer; and
	·                  the identifiable benefit can be obtained from a party other than the customer; and
	·                  the Company can reasonably estimate the fair value of the identifiable benefit
	then the payments are accounted for separate from the revenue received from that customer. If, however, all these criteria are not satisfied, then the payments are treated as a reduction of revenue from that customer.
	If the Company determines that any potential future payments to its customers are to be considered as a reduction of revenue, it must determine whether the total amount of revenue to be received under the arrangement is fixed and determinable. If the total amount of revenue is not fixed and determinable due to the uncertain nature of the potential future payments to the customer, then any customer payments cannot be recognized as revenue until the total arrangement consideration becomes fixed and determinable.
	For the reimbursements for research and development costs under collaboration agreements that meet the criteria for revenue recognition the Company has the following accounting policies:
	·                  Research and development expenses related to a collaboration agreement will be recorded on a gross basis in the income statement and not presented net of any reimbursement received from a collaboration agreement; and
	·                  The reimbursement of research and development expenses from a collaborator will be recognized in the income statement as “Research Revenue” for the period in which the research activity occurred.
	In order to determine the revenue recognition for contingent milestones, the Company evaluates the contingent milestones using the criteria as provided by the Financial Accounting Standards Boards (FASB) guidance on the milestone method of revenue recognition at the inception of a collaboration agreement. The criteria requires that (i) the Company determines if the milestone is commensurate with either its performance to achieve the milestone or the enhancement of value resulting from the Company’s activities to achieve the milestone, (ii) the milestone be related to past performance, and (iii) the milestone be reasonable relative to all deliverable and payment terms of the collaboration arrangement. If these criteria are met then the contingent milestones can be considered as substantive milestones and will be recognized as revenue in the period that the milestone is achieved.
	Fair Value Measurements
	The Company records certain asset and liability balances under the fair value measurements as defined by the FASB guidance.  Current FASB fair value guidance emphasizes that fair value is a market-based measurement, not an entity-specific measurement.  Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability.  As a basis for considering market participant assumptions in fair value measurements, current FASB guidance establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions that market participants assumptions would use in pricing assets or liabilities (unobservable inputs classified within Level 3 of the hierarchy).
	Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at measurement date.  Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly.  Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity.  In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety.  The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
	New Accounting Standards
	In February 2013, the FASB amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified as net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012.  The Company adopted these new provisions for the quarterly period beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact on the Company’s consolidated results of operations or financial position.

Cash_Money_Market_Funds_and_Ma

Cash, Money Market Funds and Marketable Securities	9 Months Ended
	Sep. 30, 2013
Cash, Money Market Funds and Marketable Securities	'
Cash, Money Market Funds and Marketable Securities	'
	Note 2.  Cash, Money Market Funds and Marketable Securities
	As of September 30, 2013, the Company held $30.0 million in cash and cash equivalents and $30.4 million of available-for-sale investment securities which are reported at fair value on the Company’s balance sheet.  Unrealized holding gains and losses are reported within accumulated other comprehensive income/(loss) in the statements of comprehensive loss.  If a decline in the fair value of a marketable security below the Company’s cost basis is determined to be other than temporary, such marketable security is written down to its estimated fair value as a new cost basis and the amount of the write-down is included in earnings as an impairment charge.  To date, only temporary impairment adjustments have been recorded.
	Consistent with the Company’s investment policy, the Company does not use derivative financial instruments in its investment portfolio.  The Company regularly invests excess operating cash in deposits with major financial institutions, money market funds, notes issued by the U.S. government, as well as fixed income investments and U.S. bond funds both of which can be readily purchased and sold using established markets.  The Company believes that the market risk arising from its holdings of these financial instruments is mitigated as many of these securities are either government backed or of the highest credit rating.
	Cash and available for sale securities consisted of the following as of December 31, 2012 and September 30, 2013 (in thousands):
		As of December 31, 2012
		Cost		Unrealized		Unrealized			Fair
				Gain		Loss			Value
	Cash balances	$	33,971	$	—	$	—		$	33,971
	Corporate debt securities	42,503		5		(11		)	42,497
	Commercial paper	19,725		19		—			19,744
	Certificate of deposit	2,909		1		—			2,910
		$	99,108	$	25	$	(11	)	$	99,122
	Included in cash and cash equivalents	$	33,971	$	—	$	—		$	33,971
	Included in marketable securities	65,137		25		(11		)	65,151
	Total cash and available for sale securities	$	99,108	$	25	$	(11	)	$	99,122
		As of September 30, 2013
		Cost		Unrealized		Unrealized			Fair
				Gain		Loss			Value
	Cash balances	$	30,047	$	—	$	—		$	30,047
	Corporate debt securities	21,100		2		(4		)	21,098
	Commercial paper	8,993		7		—			9,000
	Certificate of deposit	350		—		—			350
		$	60,490	$	9	$	(4	)	$	60,495
	Included in cash and cash equivalents	$	30,047	$	—	$	—		$	30,047
	Included in marketable securities	30,443		9		(4		)	30,448
	Total cash and available for sale securities	$	60,490	$	9	$	(4	)	$	60,495
	Unrealized gains and losses are reported as a component of other comprehensive income/(loss) in the statements of comprehensive loss.  For the year ended December 31, 2012, unrealized holding gains included in the statement of comprehensive loss were approximately $10,000.  For the nine months ended September 30, 2013, unrealized holding losses included in the statements of comprehensive loss were approximately $9,000.
	For the year ended December 31, 2012 and the nine months ended September 30, 2013, there were no realized gains or losses.  The cost of securities sold is based on the specific identification method.
	Unrealized loss positions in the available for sale securities as of December 31, 2012 and September 30, 2013 reflect temporary impairments that have not been recognized and have been in a loss position for less than twelve months.  The fair value of these available for sale securities in unrealized loss positions was $33.1 million and $14.8 million as of December 31, 2012 and September 30, 2013, respectively.
	The Company holds available-for-sale investment securities which are reported at fair value on the Company’s balance sheet. Unrealized holding gains and losses are reported within accumulated other comprehensive income (“AOCI”) in the statements of comprehensive loss.  The changes in AOCI associated with the unrealized holding gain on available-for-sale investments during the three and nine month period ended September 30, 2012 and 2013, were as follows (in thousands):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2012		2013		2012			2013
	Balance, beginning	$	17	$	3	$	4		$	14
	Current period changes in fair value, (a)	20		2		33			(9		)
	Reclassification of earnings, (a)	—		—		—			—
	Balance, ending	$	37	$	5	$	37		$	5
	(a) — Taxes have not been accrued on the unrealized gain on securities as the Company is in a loss position for all periods presented.

Basic_and_Diluted_Net_Loss_Att

Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share	9 Months Ended
	Sep. 30, 2013
Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share	'
Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share	'
	Note 3.   Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share
	The Company calculates net loss per share as a measurement of the Company’s performance while giving effect to all dilutive potential common shares that were outstanding during the reporting period.  The Company has a net loss for all periods presented; accordingly, the inclusion of common stock options and warrants would be anti-dilutive.  Therefore, the weighted average shares used to calculate both basic and diluted earnings per share are the same.
	The following table provides a reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In thousands, except share amounts)	2012			2013			2012			2013
	Historical
	Numerator:
	Net loss attributable to common stockholders	$	(16,290	)	$	(14,589	)	$	(38,770	)	$	(47,396	)
	Denominator
	Weighted average common shares outstanding — basic and diluted	48,513,647			49,621,188			44,255,885			49,621,188
	Dilutive common stock equivalents would include the dilutive effect of common stock options and warrants for common stock equivalents.  Potentially dilutive common stock equivalents totaled approximately 10.4 million and 11.5 million for the nine months ended September 30, 2012 and 2013, respectively.  Potentially dilutive common stock equivalents were excluded from the diluted earnings per share denominator for all periods because of their anti-dilutive effect.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2013
Stockholders' Equity	'
Stockholders' Equity	'
	Note 4.   Stockholders’ Equity
	Common Stock and Warrants
	As of September 30, 2013, the Company was authorized to issue 125 million shares of common stock. Dividends on common stock will be paid when, and if declared by the Company’s board of directors. Each holder of common stock is entitled to vote on all matters and is entitled to one vote for each share held.
	In July 2012, Amicus and GSK entered into the SPA pursuant to which GSK purchased 2.9 million unregistered shares of the Company’s common stock at a price of $6.30 per share. The total purchase price for these shares was $18.6 million. The Company received all proceeds from the sale of such shares on July 26, 2012. As of September 30, 2013, GSK had a 19.8% ownership position in the Company.
	In March 2012, the Company sold 11.5 million shares of its common stock at a public offering price of $5.70 through a Registration Statement on Form S-3 that was declared effective by the Securities and Exchange Commission (the “SEC”) on May 27, 2009. The aggregate offering proceeds were $65.6 million.
	In October 2010, GSK purchased approximately 6.9 million shares of the Company’s common stock at $4.56 per share, in connection with the Original Collaboration Agreement. The total value of this equity investment was approximately $31.0 million.
	In March 2010, the Company sold 4.9 million shares of its common stock and warrants to purchase 1.9 million shares of common stock in a registered direct offering to a selected group of institutional investors through a Registration Statement on Form S-3 that was declared effective by the SEC on May 27, 2009. The shares of common stock and warrants were sold in units consisting of one share of common stock and one warrant to purchase 0.375 shares of common stock at a price of $3.74 per unit. The warrants have a term of four years and are exercisable any time on or after the nine month anniversary of the date they were issued, at an exercise price of $4.43 per share. The gross offering proceeds were $18.5 million. There were approximately 1.4 million warrants outstanding at September 30, 2013.
	Stock Option Plans
	During the three and nine months ended September 30, 2013, the Company recorded stock based compensation expense of approximately $1.5 million and $4.7 million, respectively.  The stock-based compensation expense had no impact on the Company’s cash flows from operations and financing activities.  As of September 30, 2013, the total unrecognized compensation cost related to non-vested stock options granted was $10.0 million and is expected to be recognized over a weighted average period of 2.4 years.  The following table summarizes information related to stock compensation expense recognized in the statements of operations (in thousands):
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
		2012			2013			2012			2013
	Stock compensation expense recognized in:
	Research and development expense	$	955		$	824		$	2,748		$	2,634
	General and administrative expense	643			693			1,995			2,040
	Total stock compensation expense	$	1,598		$	1,517		$	4,743		$	4,674
	The fair value of the options granted is estimated on the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
		2012			2013			2012			2013
	Expected stock price volatility	76.2		%	81.7		%	77.5		%	82		%
	Risk free interest rate	0.9		%	1.8		%	0.8		%	1.3		%
	Expected life of options (years)	6.25			6.25			6.25			6.25
	Expected annual dividend per
	share	$	0		$	0		$	0		$	0
	A summary of option activities related to the Company’s stock options for the nine months ended September 30, 2013 is as follows:
							Weighted
				Weighted			Average
		Number		Average			Remaining		Aggregate
		of		Exercise			Contractual		Intrinsic
		Shares		Price			Life		Value
		(in thousands)							(in thousands)
	Balance at December 31, 2012	7,974.20		$	6.35
	Options granted	2,458.80		$	3.04
	Options exercised	—		$	—
	Options forfeited	(321.8	)	$	5.08
	Balance at September 30, 2013	10,111.20		$	5.58		7.3 years		$	37.8
	Vested and unvested expected to vest, September 30, 2013	9,518.40		$	5.69		7.2 years		$	37.8
	Exercisable at September 30, 2013	5,501.20		$	6.8		6.0 years		$	37.8

ShortTerm_Borrowings_and_LongT

Short-Term Borrowings and Long-Term Debt	9 Months Ended
	Sep. 30, 2013
Short-Term Borrowings and Long-Term Debt	'
Short-Term Borrowings and Long-Term Debt	'
	Note 5.  Short-Term Borrowings and Long-Term Debt
	In August 2011, the Company entered into a loan and security agreement (the “2011 Loan Agreement”) with Silicon Valley Bank (SVB), in order to finance certain capital expenditures that the Company made in connection with its move in March 2012 to new office and laboratory space in Cranbury, New Jersey. The 2011 Loan Agreement provides for up to $3.0 million of equipment financing through January 2014. Borrowings under the 2011 Loan Agreement are collateralized by equipment purchased with the proceeds of the loan and bear interest at a variable rate of SVB prime + 2.5%. The current SVB prime rate is 4.0%. In February 2012, the Company borrowed approximately $1.0 million under the 2011 Loan Agreement that will be repaid over the following 2.5 years. The 2011 Loan Agreement contains customary terms and conditions, including a financial covenant whereby the Company must maintain a minimum amount of liquidity measured at the end of each month where unrestricted cash, cash equivalents, and marketable securities, are greater than $20 million plus outstanding debt due to SVB. The Company has at all times been in compliance with these covenants during the term of the agreement.
	At September 30, 2013, the total amount due under the 2011 Loan Agreement was $0.4 million.  The carrying amount of the Company’s borrowings approximates fair value at September 30, 2013.

Assets_and_Liabilities_Measure

Assets and Liabilities Measured at Fair Value	9 Months Ended
	Sep. 30, 2013
Assets and Liabilities Measured at Fair Value	'
Assets and Liabilities Measured at Fair Value	'
	Note 6.  Assets and Liabilities Measured at Fair Value
	The Company’s financial assets and liabilities are measured at fair value and classified within the fair value hierarchy which is defined as follows:
	Level 1 — Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2 — Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly.
	Level 3 — Inputs that are unobservable for the asset or liability.
	Cash, Money Market Funds and Marketable Securities
	The Company classifies its cash and money market funds within the fair value hierarchy as Level 1 as these assets are valued using quoted prices in active market for identical assets at the measurement date.  The Company considers its investments in marketable securities as available for sale and classifies these assets within the fair value hierarchy as Level 2 primarily utilizing broker quotes in a non-active market for valuation of these securities.   No changes in valuation techniques or inputs occurred during the three or nine months ended September 30, 2013.  No transfers of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the three or nine months ended September 30, 2013.
	Secured Debt
	As disclosed in Note 5, the Company entered into the 2011 Loan Agreement with SVB.  The carrying amount of the Company’s borrowings approximates fair value at September 30, 2013.  The Company’s secured debt is classified as Level 2 and the fair value is estimated using quoted prices for similar liabilities in active markets, as well as inputs that are observable for the liability (other than quoted prices), such as interest rates that are observable at commonly quoted intervals.
	Warrants
	The Company allocated $3.3 million of proceeds from its March 2010 registered direct offering to warrants issued in connection with the offering that was classified as a liability.  The valuation of the warrants is determined using the Black-Scholes model. This model uses inputs such as the underlying price of the shares issued when the warrant is exercised, volatility, risk free interest rate and expected life of the instrument.  The Company has determined that the warrant liability should be classified within Level 3 of the fair value hierarchy by evaluating each input for the Black-Scholes model against the fair value hierarchy criteria and using the lowest level of input as the basis for the fair value classification.  There are six inputs: closing price of the Company’s stock on the day of evaluation; the exercise price of the warrants; the remaining term of the warrants; the volatility of the Company’s stock over that term; annual rate of dividends; and the riskless rate of return.  Of those inputs, the exercise price of the warrants and the remaining term are readily observable in the warrant agreements.  The annual rate of dividends is based on the Company’s historical practice of not granting dividends. The closing price of Amicus stock would fall under Level 1 of the fair value hierarchy as it is a quoted price in an active market.  The riskless rate of return is a Level 2 input, while the historical volatility is a Level 3 input in accordance with the fair value accounting guidance.  Since the lowest level input is a Level 3, the Company determined the warrant liability is most appropriately classified within Level 3 of the fair value hierarchy.  This liability is subject to fair value mark-to-market adjustment each period and approximately 0.5 million warrants were exercised in 2012.  The weighted average assumptions used in the Black-Scholes valuation model for the warrants are as follows:
		Nine Months Ended September 30,
		2012			2013
	Expected stock price volatility	76		%	59.7		%
	Risk free interest rate	0.19		%	0.03		%
	Expected life of warrants (years)	1.42			0.42
	Expected annual dividend per share	$	0		$	0
	A summary of the fair value of the Company’s assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2012, are identified in the following table (in thousands):
		Balance as of December 31, 2012
		Level 1			Level 2			Total
	Assets:
	Cash/Money market funds	$	33,971		$	—		$	33,971
	Corporate debt securities	—			42,497			42,497
	Commercial paper	—			19,744			19,744
	Certificate of deposit	—			2,910			2,910
		$	33,971		$	65,151		$	99,122
		Level 1			Level 2			Level 3		Total
	Liabilities:
	Secured debt	$	—		$	697		$	—	$	697
	Warrants liability	—			—			908		908
		$	—		$	697		$	908	$	1,605
	A summary of the fair value of the Company’s assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of September 30, 2013, are identified in the following table (in thousands):
		Balance as of September 30, 2013
		Level 1			Level 2			Total
	Assets:
	Cash/Money market funds	$	30,047		$	—		$	30,047
	Corporate debt securities				21,098			21,098
	Commercial paper	—			9,000			9,000
	Certificate of deposit	—			350			350
		$	30,047		$	30,448		$	60,495
		Level 1			Level 2			Level 3		Total
	Liabilities:
	Secured debt	$	—		$	398		$	—	$	398
	Warrants liability	—			—			34		34
		$	—		$	398		$	34	$	432
	The change in the fair value of the Level 3 liability was a decrease of $0.5 million and $0.6 million for the three months ended September 30, 2013, and 2012, respectively.  The change in fair value for the Level 3 liability was a decrease of $0.9 million and an increase of $1.9 million for the nine months ended September 30, 2013 and 2012, respectively.

Collaborative_Agreements

Collaborative Agreements	9 Months Ended
	Sep. 30, 2013
Collaborative Agreements	'
Collaborative Agreements	'
	Note 7.  Collaborative Agreements
	GSK
	On October 28, 2010, the Company entered into the Original Collaboration Agreement with Glaxo Group Limited, an affiliate of GSK, to develop and commercialize migalastat HCl. Under the terms of the Original Collaboration Agreement, GSK received an exclusive worldwide license to develop, manufacture and commercialize migalastat HCl. In consideration of the license grant, the Company received an upfront, license payment of $30.0 million from GSK and was eligible to receive further payments of approximately $173.5 million upon the successful achievement of development, regulatory and commercialization milestones, as well as tiered double-digit royalties on global sales of migalastat HCl. Potential payments included up to (i) $13.5 million related to the attainment of certain clinical development objectives and the acceptance of regulatory filings in select worldwide markets, (ii) $80.0 million related to market approvals for migalastat HCl in selected territories throughout the world, and (iii) $80.0 million associated with the achievement of certain sales thresholds. GSK and the Company were jointly funding development costs in accordance with an agreed upon development plan. Additionally, GSK purchased approximately 6.9 million shares of the Company’s common stock at $4.56 per share, a 30% premium on the average price per share of the Company’s stock over a 60 day period preceding the closing date of the transaction. The total value of this equity investment to the Company was approximately $31.0 million.
	On July 17, 2012, the Company entered into the Expanded Collaboration Agreement with GSK pursuant to which the Company and GSK continue to develop and commercialize migalastat HCl, currently in Phase 3 development for the treatment of Fabry disease. The Expanded Collaboration Agreement amends and replaces in its entirety the Original Collaboration Agreement. Under the terms of the Expanded Collaboration Agreement, the Company and GSK will co-develop all formulations of migalastat HCl for Fabry disease, including the development of migalastat HCl co-formulated with an investigational ERT for Fabry disease in collaboration with another GSK collaborator JCR Pharmaceutical Co. Ltd. The Company will commercialize all migalastat HCl products for Fabry disease in the United States while GSK will commercialize all such products in the rest of the world.
	The exclusive license granted to GSK under the Original Collaboration Agreement to commercialize migalastat HCl worldwide was replaced under the Expanded Collaboration Agreement, which grants two exclusive licenses: (i) an exclusive license from GSK to the Company to commercialize migalastat HCl in the United States, and (ii) an exclusive license from the Company to GSK to commercialize migalastat HCl in the rest of world. Amicus and GSK each have a license to manufacture migalastat HCl for commercialization of monotherapy and chaperone-ERT co-administration migalastat HCl products while GSK maintains an exclusive license to manufacture such products for development purposes (subject to limited exceptions) and to manufacture the Co-formulated Product. In the event of a change of control in the Company during the term of the Expanded Collaboration Agreement, GSK has the option to purchase an exclusive license to develop, manufacture and commercialize migalastat HCl in the United States.
	GSK is eligible to receive U.S. regulatory approval milestones totaling $20.0 million for migalastat HCl monotherapy and migalastat HCl-ERT co-administration, and additional regulatory approval and product launch milestone payments totaling up to $35.0 million within seven years following the launch of the Co-formulated Product. The Company will also be responsible for certain pass-through milestone payments and single-digit royalties on the net U.S. sales of the Co-formulated Product that GSK must pay to a third party. In addition, the Company is no longer eligible to receive any milestones or royalties it would have been eligible to receive under the Original Collaboration Agreement other than a $3.5 million clinical development milestone achieved in the second quarter of 2012 and paid by GSK to Amicus in the third quarter of 2012.
	The Company and GSK will continue to jointly fund development costs for all formulations of migalastat HCl in accordance with agreed upon development plans pursuant to which the Company and GSK funded 25% and 75% of such costs, respectively, for the monotherapy and co-administration programs during 2012 and 40% and 60%, respectively, in 2013 and beyond. Effective upon entry into the Expanded Collaboration Agreement, costs for the development of the Co-formulated Product are also funded 40% and 60% between Amicus and GSK, respectively.
	Additionally, simultaneous with entry into the Expanded Collaboration Agreement, Amicus and GSK entered into an SPA pursuant to which GSK purchased approximately 2.9 million shares of Amicus common stock at a price of $6.30 per share. The SPA provides GSK with customary registration rights for the shares purchased and includes a six-month lock-up provision. The total purchase price was $18.6 million and the Company received all proceeds from the sale of such shares on July 26, 2012. As of September 30, 2013, GSK had a 19.8% ownership position in the Company as a result of the Original Collaboration Agreement and the Expanded Collaboration Agreement.
	Under the Original Collaboration Agreement, the upfront license fee, together with the premium received on the stock purchase, was being recognized as Collaboration Revenue over the original development period. In addition, the Company was receiving reimbursements of research expenditures under the cost sharing arrangement which was being accounted for as Research Revenue on the statement of operations. Under the Expanded Collaboration Agreement, the Company will continue to receive research expense reimbursements for the development of migalastat HCl but may be required to pay contingent milestones to GSK in the future related to the U.S. commercial rights to migalastat HCl.
	In accordance with the revenue recognition guidance related to multiple-element arrangements, the Company identified all of the deliverables at the inception of the Expanded Collaboration Agreement. The significant deliverables were determined to be the rest of world licensing rights to migalastat HCl, the research services to continue and complete the development of migalastat HCl and the delivery of the Company’s common stock. The Company determined that the rest of world licensing rights and the research services represent one unit of accounting as none of these deliverables on its own has standalone value separate from the other. The Company also determined that the delivery of the Company’s common stock does have standalone value separate from the rest of world licensing rights and the research services. As a result, the Company’s common stock was considered a separate unit of accounting and was accounted for as an issuance of common stock. However, as the Company’s common stock was sold at a premium to the market closing price, the premium amount paid over the market closing price was determined to be additional consideration paid to the Company for the collaboration agreement and was included as consideration for the single unit of accounting (rest of world licensing rights and research services) identified above.
	In evaluating the impact of the Expanded Collaboration Agreement, the Company applied the accounting guidance regarding the impact of potential future payments it may make in its role as a vendor (i.e.,Amicus) to its customer (GSK) and evaluated if these potential future payments could be a reduction of revenue from GSK. If the potential future payments to GSK are as follows:
	·      a payment for an identifiable benefit, and
	·      the identifiable benefit is separable from the existing relationship between the Company and GSK, and
	·      the identifiable benefit can be obtained from a party other than GSK, and
	·      the Company can reasonably estimate the fair value of the identifiable benefit,
	then the potential future payments would be treated separately from the collaboration and research revenue. However, if all these criteria are not satisfied, then the potential future payments are treated as a reduction of revenue.
	Accordingly, the Company does not believe that, for accounting purposes, the new U.S. licensing rights to migalastat HCl obtained from GSK represent a separate, identifiable benefit from the licenses in the Original Collaboration Agreement. The contingent amounts payable to GSK are not sufficiently separable from GSK’s original license and the research and development reimbursements such that Amicus could not have entered into a similar exchange transaction with another party. Additionally, the Company cannot reasonably estimate the fair value of the US licensing rights to migalastat HCl.
	The Company determined that the potential future payments to GSK would be treated as a reduction of revenue and that the total amount of revenue to be received under the arrangement is no longer fixed or determinable as the contingent milestone payments are subject to significant uncertainty.
	As a result, the Company no longer recognizes any of the upfront license fees and premiums on the equity purchase from GSK until such time as the arrangement consideration becomes fixed or determinable, because an indeterminable amount may ultimately be payable back to GSK. These amounts (the balance of the unrecognized upfront license fee and the premium on the equity purchases) are classified as deferred reimbursements on the balance sheet.
	The recognition of Research Revenue is also affected by the determination that the overall total arrangement consideration is no longer fixed and determinable, despite the fact that the research activities will continue and that the research expense reimbursements by GSK to Amicus will be received as the research activities related to the reimbursement would have already been completed. Therefore any research reimbursements from GSK are recorded as deferred reimbursements on the balance sheet and not recognized until the total arrangement consideration becomes fixed and determinable.
	As a result, all revenue recognition was suspended until the total arrangement consideration becomes fixed and determinable. In addition, future milestone payments made by the Company will be applied against the balance of this deferred reimbursements account.  In the third quarter of 2013, we paid GSK a pass-through milestone payment of $0.8 million in connection with the development of the Co-formulated product.  This payment is reflected as a reduction of the deferred reimbursements in the Consolidated Balance Sheet as of September 30, 2013.
	Revenue recognition for research expense reimbursements, the original upfront license fee, and the equity premiums will resume once the total arrangement consideration becomes fixed and determinable which will occur when the balance of the deferred reimbursements account is sufficient to cover all the remaining contingent milestone payments.
	Under the Original Collaboration Agreement, the Company evaluated the contingent milestones and determined that they were substantive milestones and would be recognized as revenue in the period that the milestone is achieved. The Company determined that the research based milestones were commensurate with the enhanced value of each delivered item as a result of the Company’s specific performance to achieve the milestones. The research-based milestones would have related to past performances when achieved and were reasonable in relation to the other payment terms within the Original Collaboration Agreement. In September 2012, the Company achieved a clinical development milestone and recognized $3.5 million of milestone revenue. Under the terms of the Expanded Collaboration Agreement, the Company is no longer entitled to receive any milestone payments from GSK.
	Biogen Idec
	On September 10, 2013, the Company entered into a license and collaboration agreement (the “Biogen Agreement”) with Biogen to discover, develop and commercialize novel small molecules for the treatment of Parkinson’s disease. Under terms of the multi-year agreement, the Company and Biogen will collaborate in the discovery of a new class of small molecules that target the GCase enzyme, for further development and commercialization by Biogen.  Biogen will be responsible for funding all discovery, development, and commercialization activities.  In addition the Company will be reimbursed for all full-time employees working on the project as part of a cost sharing arrangement.  The Company is also eligible to receive development and regulatory milestones, as well as modest royalties in global net sales.
	In accordance with the revenue recognition guidance related to reimbursement of research and development expenses, the Company identified all deliverables at the inception of the agreement.  The Company has not commenced its planned principal operations (i.e. selling commercial products) and is therefore a development stage enterprise.  The Company is only performing development of its compounds, and therefore, development activities are part of the Company’s ongoing central operations.  Additionally, the Company has the following accounting policies:
	·                  Research and development expenses related to a collaboration agreement will be recorded on a gross basis in the income statement and not presented net of any reimbursement received from a collaboration agreement; and
	·                  The reimbursement of research and development expenses from a collaborator will be recognized in the income statement as “Research Revenue” for the period in which the research activity occurred.
	As of September 30, 2013, the Company recognized $0.04 million in Research Revenue for work performed under the cost sharing arrangement of the Biogen Agreement.
	The Company evaluated the contingent milestones included in the Biogen Agreement at the inception of the Biogen Agreement and determined that the contingent milestones are substantive milestones and will be recognized as revenue in the period that the milestone is achieved.  The Company determined that the research based milestones are commensurate with the enhanced value of each delivered item as a result of the Company’s specific performance to achieve the milestones.  The research based milestones would relate to past performances when achieved and are reasonable relative to the other payment terms within the Biogen Agreement, including the cost sharing arrangement.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events	'
Subsequent Events	'
	Note 8.  Subsequent Events
	The Company evaluated events that occurred subsequent to September 30, 2013 through the date of issuance of these financial statements and concluded that there were no material or non-recognized events during this period.

Description_of_Business_and_Si1

Description of Business and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Description of Business and Significant Accounting Policies	'
Basis of Presentation	'
	Basis of Presentation
	The Company has prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X.  Accordingly, the unaudited consolidated financial statements do not include all of the information and disclosures required by U.S. GAAP for complete financial statements.  In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information.
	The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the Company’s financial statements and related notes as contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012.  For a complete description of the Company’s accounting policies, please refer to the Annual Report on Form 10-K for the fiscal year ended December 31, 2012.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue when amounts are realized or realizable and earned.  Revenue is considered realizable and earned when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred or services have been rendered; (3) the price is fixed or determinable; and (4) collection of the amounts due are reasonably assured.
	In multiple element arrangements, revenue is allocated to each separate unit of accounting and each deliverable in an arrangement is evaluated to determine whether it represents separate units of accounting. A deliverable constitutes a separate unit of accounting when it has standalone value and there is no general right of return for the delivered elements. In instances when the aforementioned criteria are not met, the deliverable is combined with the undelivered elements and the allocation of the arrangement consideration and revenue recognition is determined for the combined unit as a single unit of accounting. Allocation of the consideration is determined at arrangement inception on the basis of each unit’s relative selling price.  In instances where there is determined to be a single unit of accounting, the total consideration is applied as revenue for the single unit of accounting and is recognized over the period of inception through the date when the last deliverable within the single unit of accounting is expected to be delivered.
	The Company’s current revenue recognition policies, which were adopted and first applied in fiscal 2010, provide that, when a collaboration arrangement contains multiple deliverables, such as license and research and development services, the Company allocates revenue to each separate unit of accounting based on a selling price hierarchy. The selling price hierarchy for a deliverable is based on (i) its vendor specific objective evidence (“VSOE”) if available, (ii) third party evidence (“TPE”) if VSOE is not available, or (iii) best estimated selling price (“BESP”) if neither VSOE nor TPE is available. The Company would establish the VSOE of selling price using the price charged for a deliverable when sold separately. The TPE of selling price would be established by evaluating largely similar and interchangeable competitor products or services in standalone sales to similarly situated customers. The BESP would be established considering internal factors such as an internal pricing analysis or an income approach using a discounted cash flow model.
	The Company also considers the impact of potential future payments it makes in its role as a vendor to its customers and evaluates if these potential future payments could be a reduction of revenue from that customer. If the potential future payments to the customer are as follows:
	·                  a payment for an identifiable benefit; and
	·                  the identifiable benefit is separable from the existing relationship between the Company and its customer; and
	·                  the identifiable benefit can be obtained from a party other than the customer; and
	·                  the Company can reasonably estimate the fair value of the identifiable benefit
	then the payments are accounted for separate from the revenue received from that customer. If, however, all these criteria are not satisfied, then the payments are treated as a reduction of revenue from that customer.
	If the Company determines that any potential future payments to its customers are to be considered as a reduction of revenue, it must determine whether the total amount of revenue to be received under the arrangement is fixed and determinable. If the total amount of revenue is not fixed and determinable due to the uncertain nature of the potential future payments to the customer, then any customer payments cannot be recognized as revenue until the total arrangement consideration becomes fixed and determinable.
	For the reimbursements for research and development costs under collaboration agreements that meet the criteria for revenue recognition the Company has the following accounting policies:
	·                  Research and development expenses related to a collaboration agreement will be recorded on a gross basis in the income statement and not presented net of any reimbursement received from a collaboration agreement; and
	·                  The reimbursement of research and development expenses from a collaborator will be recognized in the income statement as “Research Revenue” for the period in which the research activity occurred.
	In order to determine the revenue recognition for contingent milestones, the Company evaluates the contingent milestones using the criteria as provided by the Financial Accounting Standards Boards (FASB) guidance on the milestone method of revenue recognition at the inception of a collaboration agreement. The criteria requires that (i) the Company determines if the milestone is commensurate with either its performance to achieve the milestone or the enhancement of value resulting from the Company’s activities to achieve the milestone, (ii) the milestone be related to past performance, and (iii) the milestone be reasonable relative to all deliverable and payment terms of the collaboration arrangement. If these criteria are met then the contingent milestones can be considered as substantive milestones and will be recognized as revenue in the period that the milestone is achieved.
Fair Value Measurements	'
	Fair Value Measurements
	The Company records certain asset and liability balances under the fair value measurements as defined by the FASB guidance.  Current FASB fair value guidance emphasizes that fair value is a market-based measurement, not an entity-specific measurement.  Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability.  As a basis for considering market participant assumptions in fair value measurements, current FASB guidance establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions that market participants assumptions would use in pricing assets or liabilities (unobservable inputs classified within Level 3 of the hierarchy).
	Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at measurement date.  Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly.  Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity.  In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety.  The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
New Accounting Standards	'
	New Accounting Standards
	In February 2013, the FASB amended its guidance to require an entity to present the effect of certain significant reclassifications out of accumulated other comprehensive income on the respective line items in net income. The new accounting guidance does not change the items that must be reported in other comprehensive income or when an item of other comprehensive income must be reclassified as net income. The guidance is effective prospectively for fiscal years beginning after December 15, 2012.  The Company adopted these new provisions for the quarterly period beginning January 1, 2013. As the guidance requires additional presentation only, there was no impact on the Company’s consolidated results of operations or financial position.

Cash_Money_Market_Funds_and_Ma1

Cash, Money Market Funds and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Cash, Money Market Funds and Marketable Securities	'
Schedule of cash and available for sale securities	'
	Cash and available for sale securities consisted of the following as of December 31, 2012 and September 30, 2013 (in thousands):
		As of December 31, 2012
		Cost		Unrealized		Unrealized			Fair
				Gain		Loss			Value
	Cash balances	$	33,971	$	—	$	—		$	33,971
	Corporate debt securities	42,503		5		(11		)	42,497
	Commercial paper	19,725		19		—			19,744
	Certificate of deposit	2,909		1		—			2,910
		$	99,108	$	25	$	(11	)	$	99,122
	Included in cash and cash equivalents	$	33,971	$	—	$	—		$	33,971
	Included in marketable securities	65,137		25		(11		)	65,151
	Total cash and available for sale securities	$	99,108	$	25	$	(11	)	$	99,122
		As of September 30, 2013
		Cost		Unrealized		Unrealized			Fair
				Gain		Loss			Value
	Cash balances	$	30,047	$	—	$	—		$	30,047
	Corporate debt securities	21,100		2		(4		)	21,098
	Commercial paper	8,993		7		—			9,000
	Certificate of deposit	350		—		—			350
		$	60,490	$	9	$	(4	)	$	60,495
	Included in cash and cash equivalents	$	30,047	$	—	$	—		$	30,047
	Included in marketable securities	30,443		9		(4		)	30,448
	Total cash and available for sale securities	$	60,490	$	9	$	(4	)	$	60,495
Schedule of changes in AOCI associated with the unrealized holding gain on available-for-sale investments	'
	The changes in AOCI associated with the unrealized holding gain on available-for-sale investments during the three and nine month period ended September 30, 2012 and 2013, were as follows (in thousands):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2012		2013		2012			2013
	Balance, beginning	$	17	$	3	$	4		$	14
	Current period changes in fair value, (a)	20		2		33			(9		)
	Reclassification of earnings, (a)	—		—		—			—
	Balance, ending	$	37	$	5	$	37		$	5
	(a) — Taxes have not been accrued on the unrealized gain on securities as the Company is in a loss position for all periods presented.

Basic_and_Diluted_Net_Loss_Att1

Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share (Tables)	9 Months Ended
	Sep. 30, 2013
Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share	'
Schedule of reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share	'
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In thousands, except share amounts)	2012			2013			2012			2013
	Historical
	Numerator:
	Net loss attributable to common stockholders	$	(16,290	)	$	(14,589	)	$	(38,770	)	$	(47,396	)
	Denominator
	Weighted average common shares outstanding — basic and diluted	48,513,647			49,621,188			44,255,885			49,621,188

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Stockholders' Equity	'
Summary of information related to stock compensation expense recognized in the statements of operations	'
	The following table summarizes information related to stock compensation expense recognized in the statements of operations (in thousands):
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
		2012			2013			2012			2013
	Stock compensation expense recognized in:
	Research and development expense	$	955		$	824		$	2,748		$	2,634
	General and administrative expense	643			693			1,995			2,040
	Total stock compensation expense	$	1,598		$	1,517		$	4,743		$	4,674
Schedule of fair value weighted-average assumptions	'
		Three Months						Nine Months
		Ended September 30,						Ended September 30,
		2012			2013			2012			2013
	Expected stock price volatility	76.2		%	81.7		%	77.5		%	82		%
	Risk free interest rate	0.9		%	1.8		%	0.8		%	1.3		%
	Expected life of options (years)	6.25			6.25			6.25			6.25
	Expected annual dividend per
	share	$	0		$	0		$	0		$	0
Summary of option activities	'
							Weighted
				Weighted			Average
		Number		Average			Remaining		Aggregate
		of		Exercise			Contractual		Intrinsic
		Shares		Price			Life		Value
		(in thousands)							(in thousands)
	Balance at December 31, 2012	7,974.20		$	6.35
	Options granted	2,458.80		$	3.04
	Options exercised	—		$	—
	Options forfeited	(321.8	)	$	5.08
	Balance at September 30, 2013	10,111.20		$	5.58		7.3 years		$	37.8
	Vested and unvested expected to vest, September 30, 2013	9,518.40		$	5.69		7.2 years		$	37.8
	Exercisable at September 30, 2013	5,501.20		$	6.8		6.0 years		$	37.8

Assets_and_Liabilities_Measure1

Assets and Liabilities Measured at Fair Value (Tables)	9 Months Ended
	Sep. 30, 2013
Assets and Liabilities Measured at Fair Value	'
Schedule of weighted average assumptions used in the Black-Scholes valuation model for the warrants	'
		Nine Months Ended September 30,
		2012			2013
	Expected stock price volatility	76		%	59.7		%
	Risk free interest rate	0.19		%	0.03		%
	Expected life of warrants (years)	1.42			0.42
	Expected annual dividend per share	$	0		$	0
Schedule of financial assets and liabilities subject to fair value measurements	'
	A summary of the fair value of the Company’s assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2012, are identified in the following table (in thousands):
		Balance as of December 31, 2012
		Level 1			Level 2			Total
	Assets:
	Cash/Money market funds	$	33,971		$	—		$	33,971
	Corporate debt securities	—			42,497			42,497
	Commercial paper	—			19,744			19,744
	Certificate of deposit	—			2,910			2,910
		$	33,971		$	65,151		$	99,122
		Level 1			Level 2			Level 3		Total
	Liabilities:
	Secured debt	$	—		$	697		$	—	$	697
	Warrants liability	—			—			908		908
		$	—		$	697		$	908	$	1,605
	A summary of the fair value of the Company’s assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of September 30, 2013, are identified in the following table (in thousands):
		Balance as of September 30, 2013
		Level 1			Level 2			Total
	Assets:
	Cash/Money market funds	$	30,047		$	—		$	30,047
	Corporate debt securities				21,098			21,098
	Commercial paper	—			9,000			9,000
	Certificate of deposit	—			350			350
		$	30,047		$	30,448		$	60,495
		Level 1			Level 2			Level 3		Total
	Liabilities:
	Secured debt	$	—		$	398		$	—	$	398
	Warrants liability	—			—			34		34
		$	—		$	398		$	34	$	432

Description_of_Business_and_Si2

Description of Business and Significant Accounting Policies (Details) (USD $)

1 Months Ended

9 Months Ended

140 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

1 Months Ended

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

Mar. 31, 2012

Mar. 31, 2010

Sep. 30, 2012

Sep. 30, 2013

Dec. 31, 2012

Oct. 28, 2010

Oct. 31, 2010

Jul. 17, 2012

Jul. 31, 2012

Sep. 30, 2013

Jul. 26, 2012

Jul. 17, 2012

Jul. 31, 2012

Sep. 30, 2013

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

Original Collaboration Agreement

Original Collaboration Agreement

Expanded Collaboration Agreement

Expanded Collaboration Agreement

Expanded Collaboration Agreement

SPA

SPA

SPA

SPA

Corporate Information, Status of Operations and Management Plans

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of development costs funded by the entity

'

'

'

'

'

'

'

40.00%

'

'

'

'

'

'

Percentage of development costs funded by the counterparty

'

'

'

'

'

'

'

60.00%

'

'

'

'

'

'

Price per share of common stock issued as part of the license and collaboration agreement (in dollars per share)

$5.70

$3.74

'

'

'

$4.56

$4.56

'

'

'

'

$6.30

$6.30

'

Total purchase price (in dollars)

'

'

'

'

'

'

'

'

'

'

$18,600,000

$18,600,000

'

'

Ownership position in the company (as a percent)

'

'

'

'

'

'

'

'

'

19.80%

'

'

'

19.80%

Accumulated deficit

'

'

'

-366,285,000

-318,889,000

'

'

'

'

'

'

'

'

'

Common stock issued (in shares)

11.5

4.95

'

'

'

'

'

'

2.9

'

'

'

'

'

Warrants issued (in shares)

'

1.9

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from the issuance of common stock (in dollars)

62,000,000

'

80,195,000

193,441,000

'

31,000,000

31,000,000

'

18,600,000

'

'

'

'

'

Proceeds from the issuance of common stock and warrants (in dollars)

'

$17,100,000

'

'

'

'

'

'

'

'

'

'

'

'

Stock issued from collaboration agreement (in shares)

'

4.9

'

'

'

6.9

6.87

'

'

'

'

2.9

2.9

'

Cash_Money_Market_Funds_and_Ma2

Cash, Money Market Funds and Marketable Securities (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	140 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2011
Cash, Money Market Funds, and Marketable Securities	'	'	'	'	'	'	'
Cash and cash equivalents, Amortized Cost	$30,047,000	$24,273,000	$30,047,000	$24,273,000	$33,971,000	$30,047,000	$25,668,000
Cash and cash equivalents, Fair Value	30,047,000	'	30,047,000	'	33,971,000	30,047,000	'
Marketable securities, Amortized Cost	30,443,000	'	30,443,000	'	65,137,000	30,443,000	'
Unrealized Gain	9,000	'	9,000	'	25,000	9,000	'
Unrealized Loss	-4,000	'	-4,000	'	-11,000	-4,000	'
Marketable securities, Fair Value	30,448,000	'	30,448,000	'	65,151,000	30,448,000	'
Cash and marketable securities, Amortized Cost	60,490,000	'	60,490,000	'	99,108,000	60,490,000	'
Cash and marketable securities, Fair Value	60,495,000	'	60,495,000	'	99,122,000	60,495,000	'
Available-for-sale investments	'	'	'	'	'	'	'
Unrealized holding losses included in the statement of comprehensive loss	2,000	20,000	-9,000	33,000	10,000	5,000	'
Realized gain (loss) on securities available-for-sale	'	'	0	'	0	'	'
Fair value of available for sale securities in unrealized loss positions	14,800,000	'	14,800,000	'	33,100,000	14,800,000	'
Changes in AOCI associated with the unrealized holding gain on available-for-sale investments	'	'	'	'	'	'	'
Balance, beginning	3,000	17,000	14,000	4,000	4,000	'	'
Current period changes in fair value	2,000	20,000	-9,000	33,000	10,000	5,000	'
Balance, ending	5,000	37,000	5,000	37,000	14,000	5,000	'
Corporate debt securities	'	'	'	'	'	'	'
Cash, Money Market Funds, and Marketable Securities	'	'	'	'	'	'	'
Marketable securities, Amortized Cost	21,100,000	'	21,100,000	'	42,503,000	21,100,000	'
Unrealized Gain	2,000	'	2,000	'	5,000	2,000	'
Unrealized Loss	-4,000	'	-4,000	'	-11,000	-4,000	'
Marketable securities, Fair Value	21,098,000	'	21,098,000	'	42,497,000	21,098,000	'
Commercial paper	'	'	'	'	'	'	'
Cash, Money Market Funds, and Marketable Securities	'	'	'	'	'	'	'
Marketable securities, Amortized Cost	8,993,000	'	8,993,000	'	19,725,000	8,993,000	'
Unrealized Gain	7,000	'	7,000	'	19,000	7,000	'
Marketable securities, Fair Value	9,000,000	'	9,000,000	'	19,744,000	9,000,000	'
Certificate of deposit	'	'	'	'	'	'	'
Cash, Money Market Funds, and Marketable Securities	'	'	'	'	'	'	'
Marketable securities, Amortized Cost	350,000	'	350,000	'	2,909,000	350,000	'
Unrealized Gain	'	'	'	'	1,000	'	'
Marketable securities, Fair Value	$350,000	'	$350,000	'	$2,910,000	$350,000	'

Basic_and_Diluted_Net_Loss_Att2

Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share (Details) (USD $)	3 Months Ended		9 Months Ended		140 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Basic and Diluted Net Loss Attributable to Common Stockholders per Common Share	'	'	'	'	'
Net loss attributable to common stockholders	($14,589)	($16,290)	($47,396)	($38,770)	($386,511)
Weighted average common shares outstanding - basic and diluted	49,621,188	48,513,647	49,621,188	44,255,885	'
Common stock options	'	'	'	'	'
Antidilutive securities	'	'	'	'	'
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	'	'	11,500,000	10,400,000	'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	1 Months Ended		9 Months Ended	140 Months Ended		0 Months Ended		1 Months Ended		0 Months Ended	1 Months Ended
	Mar. 31, 2012	Mar. 31, 2010	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Jul. 26, 2012	Jul. 17, 2012	Jul. 31, 2012	Sep. 30, 2013	Oct. 28, 2010	Oct. 31, 2010
				item		GSK	GSK	GSK	GSK	GSK	GSK
						SPA	SPA	SPA	SPA	Original Collaboration Agreement	Original Collaboration Agreement
Stockholders' Equity	'	'	'	'	'	'	'	'	'	'	'
Authorized number of shares of common stock	'	'	'	125,000,000	125,000,000	'	'	'	'	'	'
Voting right for each share held, number	'	'	'	1	'	'	'	'	'	'	'
Collaborative Agreements	'	'	'	'	'	'	'	'	'	'	'
Stock issued from collaboration agreement (in shares)	'	4,900,000	'	'	'	'	2,900,000	2,900,000	'	6,900,000	6,870,000
Common stock issued (in shares)	11,500,000	4,950,000	'	'	'	'	'	'	'	'	'
Offering price (in dollars per share)	$5.70	$3.74	'	'	'	'	$6.30	$6.30	'	$4.56	$4.56
Total purchase price (in dollars)	'	'	'	'	'	$18,600,000	$18,600,000	'	'	'	'
Aggregate offering proceeds from issuance of common stock (in dollars)	65,600,000	18,500,000	'	'	'	'	'	'	'	'	'
Ownership position in the company (as a percent)	'	'	'	'	'	'	'	'	19.80%	'	'
Warrants issued (in shares)	'	1,900,000	'	'	'	'	'	'	'	'	'
Number of common stock sold in a unit (in shares)	'	1	'	'	'	'	'	'	'	'	'
Number of warrants sold in a unit (in shares)	'	1	'	'	'	'	'	'	'	'	'
Portion of share purchased against a unit	'	0.375	'	'	'	'	'	'	'	'	'
Warrant term	'	'4 years	'	'	'	'	'	'	'	'	'
Exercise period of warrants on or after date of issue	'	'9 months	'	'	'	'	'	'	'	'	'
Exercise price of warrants (in dollars per share)	'	$4.43	'	'	'	'	'	'	'	'	'
Proceeds from the issuance of common stock and warrants (in dollars)	$62,000,000	'	$80,195,000	$193,441,000	'	'	'	'	'	$31,000,000	$31,000,000
Warrants outstanding	'	'	'	1,400,000	'	'	'	'	'	'	'

Stockholders_Equity_Details_2

Stockholders' Equity (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock compensation expense	'	'	'	'
Total stock compensation expense	$1,517	$1,598	$4,674	$4,743
Research and development expense	'	'	'	'
Stock compensation expense	'	'	'	'
Total stock compensation expense	824	955	2,634	2,748
General and administrative expense	'	'	'	'
Stock compensation expense	'	'	'	'
Total stock compensation expense	$693	$643	$2,040	$1,995

Stockholders_Equity_Details_3

Stockholders' Equity (Details 3) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stockholders' Equity	'	'	'	'
Stock-based compensation expenses	$1,517,000	$1,598,000	$4,674,000	$4,743,000
Stock options plans	'	'	'	'
Stockholders' Equity	'	'	'	'
Stock-based compensation expenses	1,500,000	'	4,700,000	'
Total unrecognized compensation cost related to non-vested stock options granted (in dollars)	10,000,000	'	10,000,000	'
Period of recognition compensation cost	'	'	'2 years 4 months 24 days	'
Fair value weighted-average assumptions:	'	'	'	'
Expected stock price volatility (as a percent)	81.70%	76.20%	82.00%	77.50%
Risk free interest rate (as a percent)	1.80%	0.90%	1.30%	0.80%
Expected life of options	'6 years 3 months	'6 years 3 months	'6 years 3 months	'6 years 3 months
Expected annual dividend per share (in dollars per share)	$0	$0	$0	$0
Number of Shares	'	'	'	'
Balance at the beginning of the period (in shares)	'	'	7,974,200	'
Options granted (in shares)	'	'	2,458,800	'
Options forfeited (in shares)	'	'	-321,800	'
Balance at the end of the period (in shares)	10,111,200	'	10,111,200	'
Vested and unvested expected to vest at the end of the period (in shares)	9,518,400	'	9,518,400	'
Exercisable at the end of the period (in shares)	5,501,200	'	5,501,200	'
Weighted Average Exercise Price	'	'	'	'
Balance at the beginning of the period (in dollars per share)	'	'	$6.35	'
Options granted (in dollars per share)	'	'	$3.04	'
Options forfeited (in dollars per share)	'	'	$5.08	'
Balance at the end of the period (in dollars per share)	$5.58	'	$5.58	'
Vested and unvested expected to vest at the end of the period (in dollars per share)	$5.69	'	$5.69	'
Exercisable at the end of the period (in dollars per share)	$6.80	'	$6.80	'
Weighted Average Remaining Contractual Life	'	'	'	'
Balance at the end of the period	'	'	'7 years 3 months 18 days	'
Vested and unvested expected to vest at the end of the period	'	'	'7 years 2 months 12 days	'
Exercisable at the end of the period	'	'	'6 years	'
Aggregate Intrinsic Value	'	'	'	'
Aggregate intrinsic value of options outstanding (in dollars)	37,800	'	37,800	'
Aggregate intrinsic value of options vested and unvested expected to vest (in dollars)	37,800	'	37,800	'
Aggregate intrinsic value of options exercisable (in dollars)	$37,800	'	$37,800	'

ShortTerm_Borrowings_and_LongT1

Short-Term Borrowings and Long-Term Debt (Details) (2011 Loan Agreement, USD $)	1 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Feb. 29, 2012	Sep. 30, 2013
2011 Loan Agreement	'	'
Short-Term Borrowings and Long-Term Debt	'	'
Maximum amount of loan	'	$3
Variable interest rate base, SVB prime rate	'	'SVB prime
Percentage points added to the reference rate	'	2.50%
SVB prime rate (as a percent)	'	4.00%
Amount borrowed	1	'
Period for repayment of debt	'2 years 6 months	'
Financial covenant, minimum amount of unrestricted cash, cash equivalents and marketable securities plus all outstanding borrowings	'	20
Amount outstanding	'	$0.40

Assets_and_Liabilities_Measure2

Assets and Liabilities Measured at Fair Value (Details) (USD $)

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

Share data in Millions, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

item

Level 1

Level 1

Level 2

Level 2

Level 2

Level 2

Level 2

Level 2

Level 2

Level 2

Level 3

Level 3

Level 3

Level 3

Level 3

Total

Total

Total

Total

Total

Total

Total

Total

Corporate debt securities

Corporate debt securities

Commercial paper

Commercial paper

Certificate of deposit

Certificate of deposit

Corporate debt securities

Corporate debt securities

Commercial paper

Commercial paper

Certificate of deposit

Certificate of deposit

Assets and Liabilities Measured at Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Transfer of assets from Level 1 to Level 2

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Transfer of assets from Level 2 to Level 1

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from issuance of warrants

3,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of inputs used in fair value classification

6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants exercised (in shares)

'

'

0.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average assumptions used in the Black-Scholes valuation model for the warrants

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected stock price volatility (as a percent)

59.70%

76.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Risk free interest rate (as a percent)

0.03%

0.19%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected life of warrants

'5 months 1 day

'1 year 5 months 1 day

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected annual dividend per share (as a percent)

0.00%

0.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Assets:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash/Money market fund

30,047,000

24,273,000

33,971,000

25,668,000

30,047,000

33,971,000

'

'

'

'

'

'

'

'

'

'

'

'

'

30,047,000

33,971,000

'

'

'

'

'

'

Fair value of assets

'

'

'

'

30,047,000

33,971,000

30,448,000

65,151,000

21,098,000

42,497,000

9,000,000

19,744,000

350,000

2,910,000

'

'

'

'

'

60,495,000

99,122,000

21,098,000

42,497,000

9,000,000

19,744,000

350,000

2,910,000

Liabilities:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Secured debt

'

'

'

'

'

'

398,000

697,000

'

'

'

'

'

'

'

'

'

'

'

398,000

697,000

'

'

'

'

'

'

Warrant liability

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,000

'

34,000

'

908,000

34,000

908,000

'

'

'

'

'

'

Fair value of liabilities

'

'

'

'

'

'

398,000

697,000

'

'

'

'

'

'

34,000

'

34,000

'

908,000

432,000

1,605,000

'

'

'

'

'

'

Increase/(Decrease) in fair value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

($500,000)

($600,000)

($900,000)

$1,900,000

'

'

'

'

'

'

'

'

'

Collaborative_Agreements_Detai

Collaborative Agreements (Details) (USD $)

1 Months Ended

3 Months Ended

9 Months Ended

140 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

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

Mar. 31, 2012

Mar. 31, 2010

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Oct. 28, 2010

Oct. 31, 2010

Jul. 17, 2012

Jul. 31, 2012

Sep. 30, 2013

Jul. 26, 2012

Jul. 17, 2012

Jul. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2012

Oct. 28, 2010

Oct. 28, 2010

Oct. 28, 2010

Jul. 17, 2012

Jul. 17, 2012

Jul. 17, 2012

Sep. 30, 2013

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

GSK

Biogen Idec

item

Original Collaboration Agreement

Original Collaboration Agreement

Expanded Collaboration Agreement

Expanded Collaboration Agreement

Expanded Collaboration Agreement

SPA

SPA

SPA

SPA

Clinical development objectives and the acceptance of regulatory filings milestone

Clinical development objectives and the acceptance of regulatory filings milestone

Clinical development objectives and the acceptance of regulatory filings milestone

Market approvals for migalastat HCl milestone

Achievement of certain sales thresholds milestone

U.S. regulatory approval milestones for migalastat HCl monotherapy and migalastat HCl-ERT co-administration

U.S. regulatory approval milestones for migalastat HCl monotherapy and migalastat HCl-ERT co-administration

U.S. regulatory approval milestones for migalastat HCl monotherapy and migalastat HCl-ERT co-administration

item

Original Collaboration Agreement

Original Collaboration Agreement

Original Collaboration Agreement

Original Collaboration Agreement

Expanded Collaboration Agreement

Expanded Collaboration Agreement

Maximum

Collaborative Agreements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Upfront payment received

'

'

'

'

'

'

'

$30,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Potential milestone payments receivable

'

'

'

'

'

'

'

173,500,000

'

'

'

'

'

'

'

'

'

'

13,500,000

80,000,000

80,000,000

'

20,000,000

'

'

Percentage of development costs funded by the entity

'

'

'

'

'

'

'

'

'

40.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock issued from collaboration agreement (in shares)

'

4.9

'

'

'

'

'

6.9

6.87

'

'

'

'

2.9

2.9

'

'

'

'

'

'

'

'

'

'

Price per share of common stock issued as part of the license and collaboration agreement (in dollars per share)

$5.70

$3.74

'

'

'

'

'

$4.56

$4.56

'

'

'

'

$6.30

$6.30

'

'

'

'

'

'

'

'

'

'

Percentage of premium on average price per share of common stock issued as part of the license and collaboration agreement

'

'

'

'

'

'

'

30.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Period preceding the closing date of the transaction over which average price per share of the company's stock is used

'

'

'

'

'

'

'

'60 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total value of the equity investment to the company

62,000,000

'

'

'

80,195,000

193,441,000

'

31,000,000

31,000,000

'

18,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership position in the company (as a percent)

'

'

'

'

'

'

'

'

'

'

'

19.80%

'

'

'

19.80%

'

'

'

'

'

'

'

'

'

Number of accounting units

'

'

'

'

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Pass-through milestone payment

'

'

'

'

'

'

'

'

'

'

'

800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Milestone revenue recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,500,000

'

'

'

'

'

'

'

'

Number of exclusive licenses

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Additional potential milestone payments receivable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

35,000,000

'

Potential milestone payments received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,500,000

'

'

'

'

'

'

'

Period of additional potential milestone payments receivable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years

'

Percentage of development costs funded by the entity in 2012

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25.00%

'

'

'

Percentage of development costs funded by the counterparty in 2012

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

75.00%

'

'

'

Percentage of development costs funded by the entity, thereafter

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40.00%

'

'

'

Percentage of development costs funded by the counterparty, thereafter

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

Percentage of development costs funded by the counterparty

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total purchase price (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

18,600,000

18,600,000

'

'

'

'

'

'

'

'

'

'

'

Lock-up period for common stock issued as a part of SPA

'

'

'

'

'

'

'

'

'

'

'

'

'6 months

'

'

'

'

'

'

'

'

'

'

'

'

Research revenue for work performed under cost sharing arrangement

'

'

$39,000

$39,000

$11,591,000

$57,532,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$40,000