Amicus Therapeutics (FOLD) 10-K 29 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 12, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	AMICUS THERAPEUTICS INC
Entity Central Index Key	1,178,879
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,452,668,984
Entity Common Stock, Shares Outstanding		125,211,393
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 69,485	$ 24,074
Investments in marketable securities	144,548	127,601
Prepaid expenses and other current assets	2,568	2,902
Total current assets	216,601	154,577
Available-for-sale Securities, Noncurrent		17,464
Property and equipment, less accumulated depreciation of $13,353 and $11,520 at December 31, 2015 and December 31, 2014, respectively	6,178	2,811
In-process research & development	486,700	23,000
Goodwill	197,797	11,613
Other non-current assets	1,108	502
Total Assets	908,384	209,967
Current liabilities:
Accounts payable and accrued expenses	32,216	16,345
Current portion of secured loan		3,840
Current portion of contingent consideration payable	41,400
Total current liabilities	73,616	20,185
Deferred reimbursements	35,756	36,620
Secured loan, less current portion		10,510
Due to related party	41,601
Contingent consideration payable, less current portion	232,677	10,700
Deferred tax liability	176,219	9,186
Other non-current liabilities	$ 681	$ 588
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value, 250,000,000 shares authorized, 125,027,034 shares issued and outstanding at December 31, 2015, 125,000,000 shares authorized, 95,556,277 shares issued and outstanding at December 31, 2014	$ 1,306	$ 1,015
Additional paid-in capital	917,454	568,743
Accumulated other comprehensive loss	(115)	(132)
Warrants and Rights Outstanding	8,755
Accumulated Deficit	(579,566)	(447,448)
Total stockholders' equity	347,834	122,178
Total Liabilities and Stockholders' Equity	$ 908,384	$ 209,967

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheets
Accumulated depreciation of property and equipment (in dollars)	$ 13,353	$ 11,520
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	125,000,000
Common stock, shares issued	125,027,034	95,556,277
Common stock, shares outstanding	125,027,034	95,556,277

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Research revenue		$ 1,224	$ 363
Total revenue		1,224	363
Operating Expenses:
Research and development	$ 76,943	47,624	41,944
General and administrative	47,269	20,717	18,893
Changes in fair value of contingent consideration payable	4,377	100
Restructuring charges	15	(63)	1,988
Depreciation and amortization	1,833	1,547	1,719
Total operating expenses	130,437	69,925	64,544
Loss from operations	(130,437)	(68,701)	(64,181)
Other income (expenses):
Interest income	929	223	174
Interest expense	(1,578)	(1,484)	(46)
Loss on extinguishment of debt	(952)
Change in fair value of warrant liability			908
Other expense	(80)	(77)
Loss before income tax benefit	(132,118)	(70,039)	(63,145)
Income tax benefit		1,113	3,512
Net loss	$ (132,118)	$ (68,926)	$ (59,633)
Net loss per common share - basic and diluted	$ (1.20)	$ (0.93)	$ (1.16)
Weighted-average common shares outstanding - basic and diluted	109,923,815	74,444,157	51,286,059

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated Statements of Comprehensive Loss
Net loss	$ (132,118)	$ (68,926)	$ (59,633)
Other comprehensive income/ (loss):
Unrealized (loss) gain on available-for-sale securities	17	(133)	(13)
Other comprehensive (loss) gain before income taxes	17	(133)	(13)
Other comprehensive (loss)/income	17	(133)	(13)
Comprehensive loss	$ (132,101)	$ (69,059)	$ (59,646)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	SciodermCommon Stock	SciodermAdditional Paid-In Capital	Scioderm	CallidusCommon Stock	CallidusAdditional Paid-In Capital	Callidus	Common Stock	Additional Paid-In Capital	Warrants	Other Comprehensive Gain/ (Loss)	Deficit Accumulated During the Development Stage	Total
Balance at Dec. 31, 2012							$ 556	$ 387,539		$ 14	$ (318,889)	$ 69,220
Balance (in shares) at Dec. 31, 2012							49,631,672
Increase (Decrease) in Stockholders' Equity
Stock and warrants issued in financing							$ 75	14,925				15,000
Stock and warrants issued in financing (in shares)							7,500,000
Stock issued for acquisition				$ 48	$ 14,952	$ 15,000
Stock issued for acquisition (in shares)				4,843,744
Stock-based compensation								6,177				6,177
Unrealized (loss) gain on available-for-sale securities										(13)		(13)
Net loss											(59,633)	(59,633)
Balance at Dec. 31, 2013							$ 679	423,593		1	(378,522)	45,751
Balance (in shares) at Dec. 31, 2013							61,975,416
Increase (Decrease) in Stockholders' Equity
Stock issued from public offering / financing							$ 159	97,010				97,169
Stock issued from public offering / financing (in shares)							15,927,500
Stock issued at ATM transactions							$ 143	38,493				38,636
Stock issued from ATM transactions (in shares)							14,328,224
Stock issued from exercise of stock options, net							$ 10	3,663				3,673
Stock issued from exercise of stock options, net (in shares)							965,544
Stock issued for acquisition				$ 24	$ (24)
Stock issued for acquisition (in shares)				2,359,593
Stock-based compensation								6,008				6,008
Unrealized (loss) gain on available-for-sale securities										(133)		(133)
Net loss											(68,926)	(68,926)
Balance at Dec. 31, 2014							$ 1,015	568,743		(132)	(447,448)	$ 122,178
Balance (in shares) at Dec. 31, 2014							95,556,277					95,556,277
Increase (Decrease) in Stockholders' Equity
Stock issued from public offering / financing							$ 195	242,847				$ 243,042
Stock issued from public offering / financing (in shares)							19,528,302
Stock issued from exercise of stock options, net							$ 21	11,165				11,186
Stock issued from exercise of stock options, net (in shares)							2,070,300
Stock issued from exercise of warrants							$ 16	3,984				4,000
Stock issued from exercise of warrants (in shares)							1,600,000
Stock and warrants issued in financing									$ 8,755			8,755
Stock issued for acquisition	$ 59	$ 82,787	$ 82,846
Stock issued for acquisition (in shares)	5,921,771			25,762
Stock-based compensation								9,972				9,972
Restricted stock tax benefits								(2,044)				(2,044)
Restricted stock tax benefits (in shares)							324,622
Unrealized (loss) gain on available-for-sale securities										17		17
Net loss											(132,118)	(132,118)
Balance at Dec. 31, 2015							$ 1,306	$ 917,454	$ 8,755	$ (115)	$ (579,566)	$ 347,834
Balance (in shares) at Dec. 31, 2015							125,027,034					125,027,034

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net loss	$ (132,118)	$ (68,926)	$ (59,633)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash interest expense	492	277
Depreciation and amortization	1,833	1,547	1,719
Stock-based compensation	9,972	6,008	6,177
Restructuring charges	15	(63)	1,988
Change in fair value of warrant liability			(908)
Non-cash changes in the fair value of contingent consideration payable	4,377	100
Loss on extinguishment of debt	952
Changes in operating assets and liabilities:
Receivable due from collaboration agreements		1,083	2,142
Prepaid expenses and other current assets	308	2,293	(2,925)
Other non-current assets	(666)	26
Accounts payable and accrued expenses	15,467	6,169	(613)
Non-current liabilities	93	(126)
Deferred reimbursements	(864)	(57)	6,259
Net cash used in operating activities	(100,139)	(51,669)	(45,794)
Investing activities
Sale and redemption of marketable securities	290,129	55,914	83,337
Purchases of marketable securities	(289,595)	(162,752)	(56,559)
Purchases of property and equipment	(4,817)	(238)	(695)
Acquisitions, net of cash acquired	(141,060)
Net cash used in investing activities	(145,343)	(107,076)	26,083
Financing activities
Proceeds from Issuance of Common Stock	243,042	135,805	15,000
Payments of secured loan agreement	(15,291)	(299)	(398)
Payments related to deferred financing			(110)
Proceeds from secured loan agreement	50,000		14,888
Purchase of vested restricted stock units	(2,044)
Proceeds from exercise of stock options	11,186	3,673
Proceeds from exercise of warrants	4,000
Net cash provided by financing activities	290,893	139,179	29,380
Net decrease in cash and cash equivalents	45,411	(19,566)	9,669
Cash and cash equivalents at beginning of period	24,074	43,640	33,971
Cash and cash equivalents at end of period	69,485	24,074	43,640
Supplemental disclosures of cash flow information
Cash paid during the period for interest	$ 605	$ 1,186	$ 30

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2015
Description of Business
Description of Business	1. Description of Business Corporate Information, Status of Operations, and Management Plans Amicus Therapeutics, Inc. (the "Company," "we," "us," or "our") was incorporated on February 4, 2002 in Delaware and is a biopharmaceutical company focused on the discovery and development of advanced therapies to treat a range of devastating rare and orphan diseases. Our lead product candidate is a small molecule that can be used as a monotherapy and in combination with enzyme replacement therapy ("ERT") for Fabry disease. SD-101 ("Zorblisa"), a product candidate in late-stage development, is a potential first-to-market therapy for the chronic, rare connective tissue disorder Epidermolysis Bullosa ("EB"). The Company is also leveraging its biologics and Chaperon-Advanced Replacement Therapy ("CHART") platform technologies to develop next-generation ERT products for Fabry, Pompe, and other lysosomal storage disorders ("LSDs"). Our activities since inception have consisted principally of raising capital, establishing facilities, and performing research and development. The Company's Fabry franchise strategy is to develop migalastat HCl for all patients with Fabry disease — as a monotherapy for patients with amenable mutations and in combination with ERT for all other patients. The Company has submitted a marketing application for migalastat monotherapy ("Galafold") in the European Union, and plans to continue working with the U.S. Food and Drug Administration ("FDA") to determine the optimal U.S. registration pathway. In September 2015, Amicus acquired Scioderm, Inc. ("Scioderm"), which strengthens the Company's pipeline significantly with the addition of a novel, late-stage, proprietary topical cream and potential first-to-market therapy for EB. This investigational product was granted FDA breakthrough therapy designation in 2013 based on results from Phase 2 studies for the treatment of lesions in patients suffering with EB. SD-101 is currently being investigated in a Phase 3 study ("SD-005") to support global regulatory submissions and was the first-ever treatment in EB clinical studies to show improvements in wound closure across all major EB subtypes. The Company acquired Scioderm in a cash and stock transaction. At closing, the Company paid Scioderm shareholders, option holders, and warrant holders approximately $223.9 million, of which approximately $141.1 million was paid in cash and approximately $82.8 million was paid through the issuance of 5.9 million newly issued Amicus shares. The Company has agreed to pay up to an additional $361 million to Scioderm shareholders, option holders, and warrant holders upon achievement of certain clinical and regulatory milestones, and $257 million to Scioderm shareholders, option holders, and warrant holders upon achievement of certain sales milestones. If SD-101 is approved, EB qualifies as a rare pediatric disease and Amicus will request a Priority Review Voucher. If the Priority Review Voucher is obtained and subsequently sold, the Company will pay Scioderm shareholders, option holders, and warrant holders the lesser of $100 million in the aggregate or 50% of the proceeds of such sale. For more details, refer to "— Note 3. Acquisitions." In September 2015, a Pre-New Drug Application ("NDA") meeting was held with the FDA to discuss the oral small molecule pharmacological chaperone migalastat HCl for the treatment of Fabry disease. Based on FDA feedback and subsequent follow-up interactions with the agency, the Company is further evaluating several U.S. pathways including a potential submission requesting Subpart H approval, or potentially generating additional data on migalastat HCl's effect on gastrointestinal symptoms in Fabry disease to support submission requesting full approval. Based on this updated guidance, the Company expects to provide an update on the U.S. regulatory plans in the first half of 2016. In June 2015, the European Medicines Agency ("EMA") validated the Company's Marketing Authorization Application ("MAA") submission for Galafold and the Centralized Procedure has begun under Accelerated Assessment. The Committee for Medicinal Products for Human Use ("CHMP") may shorten the MAA review period from 210 days, under standard review, to 150 days under Accelerated Assessment. The CHMP opinion is then reviewed by the European Commission, which generally issues a final decision on European Union ("EU") approval within three months. The MAA submission will be reviewed in the Centralized Procedure, which if authorized, provides a marketing license valid in all 28 EU member states. Once authorized, the Company would then begin the country-by-country reimbursement approval process. Following the MAA validation, the Company is also initiating the regulatory submission process in several additional geographies. In October 2015, the Company entered into a note and warrant purchase agreement (the "October 2015 Purchase Agreement") with Redmile Capital Fund, LP and certain of its affiliates ("Redmile"), whereby it sold, on a private placement basis, (a) $50.0 million aggregate principal amount of its unsecured promissory notes ("Notes") and (b) five-year warrants ("Warrants") for 1.3 million shares of Common Stock. On February 19, 2016, the Company entered into a Note and Warrant Purchase Agreement (the "February 2016 Purchase Agreement") with Redmile for an aggregate amount of up to $75.0 million. The Company has agreed with Redmile that in full consideration of the purchase price for the notes issued under the October 2015 Purchase Agreement, Redmile surrendered for cancellation all notes and warrants acquired from the October 2015 Purchase Agreement and the Company will pay Redmile any unpaid interest accrued thereunder. For additional information, see "— Note 16. Short-Term Borrowings and Long-Term Debt" and "— Note 20. Subsequent Events." In June 2015, the Company issued a total of 19.5 million shares through a public offering at a price of $13.25 per share, with net proceeds of $243.0 million. The Company expects to use the net proceeds of the offering for investment in the global commercialization infrastructure for Galafold for Fabry disease, the continued clinical development of its product candidates and for other general corporate purposes. In November 2014, the Company issued a total of 15.9 million shares through public offering at a price of $6.50 per share, with net proceeds of $97.2 million. The Company expects to use the net proceeds of the offering for investment in the global commercialization infrastructure for migalastat monotherapy for Fabry disease, the continued clinical development of its product candidates and for other general corporate purposes. In July 2014, the Company completed a $40 million at the market ("ATM") equity offering under which the Company sold shares of its common stock, par value $0.01 per share, with Cowen and Company LLC as sales agent. Under the ATM equity program, the Company sold 14.3 million shares of common stock raising approximately $38.6 million in net proceeds. For further information on the ATM Agreement, see "— Note 9. Stockholder's Equity". In November 2013, the Company completed the acquisition of Callidus Biopharma, Inc. ("Callidus"). Callidus was a privately-held biologics company focused on developing best-in-class ERTs for lysosomal storage diseases LSDs. Callidus lead ERT is a recombinant human acid-alpha glucosidase (rhGAA, called "ATB200") for Pompe disease in late preclinical development. For further information, see "— Note 3. Acquisitions." In November 2013, the Company entered into the Revised Agreement (the "Revised Agreement") with GlaxoSmithKline plc ("GSK"), pursuant to which Amicus has obtained global rights to develop and commercialize migalastat as a monotherapy and in combination with ERT for Fabry disease. The Revised Agreement amends and replaces in its entirety the Expanded Agreement entered into between Amicus and GSK in July 2012 (the "Expanded Collaboration Agreement"). Under the terms of the Revised Agreement, Amicus obtained global commercial rights to migalastat, both as a monotherapy and co-formulated with ERT. For migalastat monotherapy, GSK is eligible to receive post-approval and sales-based milestones, as well as tiered royalties in the mid-teens in eight major markets outside the U.S. There was no other consideration paid to GSK as part of the Revised Agreement. The Company had an accumulated deficit of approximately $579.6 million at December 31, 2015 and anticipates incurring losses through the fiscal year ending December 31, 2016 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. The Company believes that its existing cash and cash equivalents and short-term investments will be sufficient to fund the current operating plan into 2017.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented. Consolidation The financial statements include the accounts of Amicus Therapeutics, Inc. and its wholly owned subsidiaries, Amicus Therapeutics UK Limited, Scioderm, Inc., Callidus Biopharma, Inc. Amicus Therapeutics UK Limited includes Amicus Therapeutics SAS, Amicus Therapeutics B.V, Amicus Therapeutics GmbH, and Amicus Therapeutics S.r.l. All significant intercompany transactions and balances are eliminated in consolidation. These subsidiaries are not material to the overall financial statements of the Company. Use of Estimates The preparation of financial statements in conformity with U.S.GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. Cash, Money Market Funds, and Marketable Securities The Company considers all highly liquid investments purchased with a maturity of three months or less at the date of acquisition, to be cash equivalents. Marketable securities consist of fixed income investments with a maturity of greater than three months and other highly liquid investments that can be readily purchased or sold using established markets. These investments are classified as available-for-sale and are reported at fair value on the Company's balance sheet. Unrealized holding gains and losses are reported within comprehensive income/ (loss) in the statements of comprehensive loss. Fair value is based on available market information including quoted market prices, broker or dealer quotations or other observable inputs. See "— Note 5. Cash, Money Market Funds and Marketable Securities", for a summary of available-for-sale securities as of December 31, 2015 and 2014. Concentration of Credit Risk The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company maintains its cash and cash equivalents in bank accounts, which, at times, exceed federally insured limits. The Company invests its marketable securities in high-quality commercial financial instruments. The Company has not recognized any losses from credit risks on such accounts during any of the periods presented. The Company believes it is not exposed to significant credit risk on cash and cash equivalents or its marketable securities. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is calculated over the estimated useful lives of the respective assets, which range from three to five years, or the lesser of the related initial term of the lease or useful life for leasehold improvements. The initial cost of property and equipment consists of its purchase price and any directly attributable costs of bringing the asset to its working condition and location for its intended use. Expenditures incurred after the fixed assets have been put into operation, such as repairs and maintenance, are charged to income in the period in which the costs are incurred. Major replacements, improvements and additions are capitalized in accordance with Company policy. 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 where the last deliverable within the single unit of accounting is expected to be delivered. The Company's current revenue recognition policies 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: · 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 evaluate if 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. The reimbursements for research and development costs under collaboration agreements that meet the criteria for revenue recognition are included in Research Revenue and the costs associated with these reimbursable amounts are included in research and development expenses. 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 is 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. Contingent Liabilities On an ongoing basis, the Company may be involved in various claims, and legal proceedings. On a quarterly basis, the Company reviews the status of each significant matter and assesses its potential financial exposure. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, the Company will accrue a liability for the estimated loss. Because of uncertainties related to claims and litigation, accruals will be based on our best estimates based on available information. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation or settlement of claims, the Company may reassess the potential liability related to these matters and may revise these estimates, which could result in a material adverse adjustments to the Company's operating results. Research and Development Costs Research and development costs are expensed as incurred. Research and development expense consists primarily of costs related to personnel, including salaries and other personnel related expenses, consulting fees and the cost of facilities and support services used in drug development. Assets acquired that are used for research and development and have no future alternative use are expensed as in-process research and development. Interest Income and Interest Expense Interest income consists of interest earned on the Company's cash and cash equivalents and marketable securities. Interest expense consists of interest incurred on capital leases and secured debt. Income Taxes The Company accounts for income taxes under the liability method. Under this method deferred income tax liabilities and assets are determined based on the difference between the financial statement carrying amounts and tax basis of assets and liabilities and for operating losses and tax credit carry forwards, using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is recorded if it is "more likely than not" that a portion or all of a deferred tax asset will not be realized. Other Comprehensive Income/ (Loss) Components of other comprehensive income/(loss) include unrealized gains and losses on available-for-sale securities and are included in the statements of comprehensive loss. Leases In the ordinary course of business, the Company enters into lease agreements for office space as well as leases for certain property and equipment. The leases have varying terms and expirations and have provisions to extend or renew the lease agreement, among other terms and conditions, as negotiated. Once the agreement is executed, the lease is assessed to determine whether the lease qualifies as a capital or operating lease. When a non-cancelable operating lease includes any fixed escalation clauses and lease incentives for rent holidays or build-out contributions, rent expense is recognized on a straight-line basis over the initial term of the lease. The excess between the average rental amount charged to expense and amounts payable under the lease is recorded in accrued expenses. Nonqualified Cash Deferral Plan In July 2014, the Board of Directors approved the Company's Cash Deferral Plan (the "Deferral Plan"), which provides certain key employees and members of the Board of Directors as selected by the Compensation Committee of the Board of Directors of the Company (the "Compensation Committee"), with an opportunity to defer the receipt of such Participant's base salary, bonus and director's fees, as applicable. The Deferral Plan is intended to be a nonqualified deferred compensation plan that complies with the provisions of Section 409A of the Internal Revenue Code (the "Code"). All of the investments held in the Deferral Plan will be classified as investments held-to-maturity and recorded at fair value with changes in the investments' fair value recognized as earnings in the period they occur. The corresponding liability for the Deferral Plan is included in other non-current liability in our consolidated balance sheets. Equity Incentive Plan In June 2014, our stockholders approved the Amended and Restated 2007 Equity Incentive Plan (the "Plan"). The amendment to the Plan makes an additional 6.0 million shares of our common stock available for issuance and increases the maximum number of shares within the Plan that may be issued as restricted stock, restricted stock units ("RSUs"), stock grants and any other similar awards from 1.1 million to 1.5 million shares. As of December 31, 2015, awards issued under the Plan include both stock options and RSUs. Stock-Based Compensation At December 31, 2015, the Company had three stock-based employee compensation plans, which are described more fully in "— Note 9. Stockholders' Equity." The Company applies the fair value method of measuring stock-based compensation, which requires a public entity to measure the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award. Loss 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 had a net loss for all periods presented; accordingly, the inclusion of common stock options, unvested restricted stock units ("RSUs") and warrants would be anti-dilutive. Therefore, the weighted average shares used to calculate both basic and diluted earnings per share are the same. See "— Note 18. Earnings per Share" for further discussion on net loss per share. Dividends The Company has not paid cash dividends on its capital stock to date. The Company currently intends to retain its future earnings, if any, to fund the development and growth of the business and does not foresee payment of a dividend in any upcoming fiscal period. Segment Information The Company currently operates in one business segment focused on the discovery, development and commercialization of advanced therapies to treat a range of devastating rare and orphan diseases. The Company is not organized by market and is managed and operated as one business. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate service lines and does not have separately reportable segments. Business Combinations The Company allocates the purchase price of acquired businesses to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets and in-process research and development ("IPR&D"). In connection with the purchase price allocations for acquisitions, the Company estimates the fair value of contingent payments utilizing a probability-based income approach inclusive of an estimated discount rate. Contingent Consideration Payable The Company determines the fair value of contingent acquisition consideration payable on the acquisition date using a probability-based income approach utilizing an appropriate discount rate. Contingent acquisition consideration payable is shown as a non-current liability on the Company's consolidated balance sheets. Changes in the fair value of the contingent acquisition consideration payable will be determined each period end and recorded on the consolidated statements of operations. Intangible Assets and Goodwill The Company records goodwill in a business combination when the total consideration exceeds the fair value of the net tangible and identifiable intangible assets acquired. Purchased IPR&D is accounted for as an indefinite lived intangible asset until the underlying project is completed, at which point the intangible asset will be accounted for as a definite lived intangible asset, or abandoned, at which point the intangible asset will be written off or partially impaired. Goodwill and indefinite lived intangible assets are assessed annually for impairment and whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. If it is determined that the full carrying amount of an asset is not recoverable, an impairment loss is recorded in the amount by which the carrying amount of the asset exceeds its fair value. Restructuring Restructuring charges are recognized as a result of actions to streamline operations and rationalize manufacturing facilities. Judgment is used when estimating the impact of restructuring plans, including future termination benefits and other exit costs to be incurred when the actions take place. Actual results could vary from these estimates. Recent Accounting Pronouncements In November 2015, the FASB issued the Accounting Standards Update ("ASU") No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The amendments in ASU 2015-17 eliminates the current requirement for organizations to present deferred tax liabilities and assets as current and noncurrent in a classified balance sheet. Instead, organizations will be required to classify all deferred tax assets and liabilities as noncurrent. The ASU is effective for financial statements beginning after December 15, 2016, and interim periods within those annual periods. The amendments may be applied prospectively to all deferred tax liabilities and assets or retrospectively to all periods presented. The Company has early adopted this standard as of December 31, 2015 on a retrospective basis and this standard had no impact on its consolidated financial statements. In September 2015, the FASB issued ASU 2015-16 Business Combinations (Topic 805 ): Simplifying the Accounting for Measurement-Period Adjustments . The amendments in ASU 2015-16 require that an acquirer recognize adjustments to estimated amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments require that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the estimated amounts, calculated as if the accounting had been completed at the acquisition date. The amendments also require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the estimated amounts had been recognized as of the acquisition date. The ASU is effective for public business entities for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been issued. The Company has early adopted this standard as of September 30, 2015 and this standard had no impact on its consolidated financial statements. In April 2015, the FASB issued ASU 2015-05, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The amendments in ASU 2015-05 provide guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The amendments do not change the accounting for a customer's accounting for service contracts. As a result of the amendments, all software licenses within the scope of Subtopic 350-40 will be accounted for consistent with other licenses of intangible assets. The ASU is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. In April 2015, the FASB issued ASU 2015-03, Interest — Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . The amendments in ASU 2015-03 are intended to simplify the presentation of debt issuance costs. These amendments require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this ASU. The ASU is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted and the Company has adopted this ASU as of December 31, 2015. The guidance in ASU 2015-03 (see paragraph 835-30-45-1A) does not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. Given the absence of authoritative guidance within ASU 2015-03 for debt issuance costs related to line-of-credit arrangements, the SEC staff stated in June 2015 that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. ASU 2015-15 Imputation of Interest adds the SEC paragraph to the Topic. The Company early adopted this ASU as of December 31, 2015 and the adoption does not have an impact on its consolidated financial statements. In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern, which defines management's responsibility to assess an entity's ability to continue as a going concern, and to provide related footnote disclosures if there is substantial doubt about its ability to continue as a going concern. The pronouncement is effective for annual reporting periods ending after December 15, 2016 with early adoption permitted. The adoption of this guidance is not expected to have a significant impact on our consolidated financial statements. In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers that outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The ASU is based on the principle that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to fulfill a contract. Entities have the option of using either a full retrospective or a modified retrospective approach for the adoption of the new standard. In July 2015, the Financial Accounting Standards Board voted to delay the effective date of this standard until the first quarter of 2018. Companies are permitted to early adopt the standard in the first quarter of 2017. Presently, the Company is assessing the effect the adoption of ASU 2014-09 will have on its consolidated financial statements.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2015
Acquisitions
Acquisitions	3. Acquisitions Acquisition of Scioderm, Inc. On September 30, 2015, Amicus acquired Scioderm, a privately-held biopharmaceutical company focused on developing innovative therapies for treating the rare disease Epidermolysis Bullosa ("EB"). The acquisition leverages the Scioderm development team's EB expertise with Amicus' global clinical infrastructure to advance SD-101 toward regulatory approvals and Amicus' commercial, patient advocacy, and medical affairs infrastructure to support a successful global launch. The acquisition of Scioderm was accounted for as a purchase of a business in accordance with FASB Accounting Standard Codification 805 Business Combinations. The Company acquired Scioderm with cash and stock. At closing, the Company paid Scioderm shareholders, option holders, and warrant holders approximately $223.9 million, of which approximately $141.1 million was paid in cash and approximately $82.8 million was paid through the issuance of approximately 5.9 million newly issued Amicus shares. The Company has agreed to pay up to an additional $361 million to Scioderm shareholders, option holders and warrant holders upon achievement of certain clinical and regulatory milestones, and $257 million to Scioderm shareholders, option holders, and warrant holders upon achievement of certain sales milestones. If SD-101 is approved, EB qualifies as a rare pediatric disease under The Food and Drug Administration Safety and Innovation Act ("FDSIA") and Amicus will request a Priority Review Voucher ("PRV") under the FDSIA, if available. If the PRV is obtained and subsequently sold, the Company will pay Scioderm shareholders, option holders, and warrant holders the lesser of $100 million in the aggregate or 50% of the proceeds of such sale. If Amicus obtains the PRV and has not entered into an agreement to sell or otherwise transfer to a third party the PRV within one year of its receipt, the shareholders 'agent may appoint a financial advisor to conduct a process to sell the PRV. If Amicus determines in its sole discretion to use the PRV, Amicus shall give the shareholders' agent written notice thereof and shall pay to the Scioderm shareholders, option holders, and warrant holders $100 million. The inability to sell the PRV after complying with the provisions, shall not give rise to any payment. The fair value of the contingent consideration payments on the acquisition date was $259.0 million. This was an estimate based on significant inputs that are not observable in the market, referred to as Level 3 inputs. Key assumptions included a range of discount rates between 0.4% and 1.1% as interpolated from the U.S. Treasury constant maturity yield curve over the time frame for clinical and regulatory milestones and a range of discount rates between 1.0% and 2.2% for revenue-based milestones. The range of outcomes and assumptions used to develop these estimates have been updated to better reflect the probability of certain milestone outcomes as of December 31, 2015 (See "— Note 10. Assets and Liabilities Measured at Fair Value", for additional discussion regarding fair value measurements of the contingent acquisition consideration payable). The Company determined the fair value of the contingent consideration to be $257.8 million at December 31, 2015, of which $35.8 million is payable in the next twelve months, resulting in a decrease in the contingent consideration payable and related gain of $1.2 million year ended December 31, 2015. The gain is recorded with the change in fair value of contingent consideration payable as part of the operating expense line item in the Consolidated Statement of Operations. See "— Note 10. Assets and Liabilities Measured at Fair Value", for additional discussion regarding fair value measurements of the contingent acquisition consideration payable. For additional information, see "— Note 4. Goodwill and Intangible Assets." The purchase price allocation was subject to completion of our analysis of the fair value of the assets and liabilities as of the effective date of the acquisition. The final valuation was completed as of December 31, 2015. The final allocation of the purchase price was as follows: (in thousands) Upfront cash payments $ Upfront equity payments Contingent acquisition consideration payable ​ ​ ​ ​ ​ Total consideration Property, plant and equipment, net Intangible assets — In-process Research and Development ("IPR&D") ​ ​ ​ ​ ​ Total identifiable assets acquired Deferred tax liability ) ​ ​ ​ ​ ​ Total liabilities assumed ) Net identifiable assets acquired Goodwill ​ ​ ​ ​ ​ Net assets acquired $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A substantial portion of the assets acquired consisted of intangible assets related to SD-101. The Company determined that the estimated acquisition-date fair value of the indefinite lived IPR&D related to the SD-101 was $463.7 million. The $167.0 million of deferred tax liabilities relates to the tax impact of future amortization or possible impairments associated with the identified intangible assets acquired or IPR&D, which are not deductible for tax purposes. The goodwill results from the recognition of the deferred tax liability on the intangible assets as well as synergies expected from the acquisition and other benefits that do not qualify for separate recognition as acquired intangible assets. None of the goodwill is expected to be deductible for income tax purposes. The Company recorded the goodwill in the consolidated balance sheet as of the acquisition date. The Company recognized $3.1 million of acquisition-related transaction costs in selling, general and administrative expenses during 2015, which consisted primarily of consulting and legal fees related to the acquisition. The following unaudited consolidated pro forma financial information presents the combined results of operations of the Company and Scioderm as if the acquisition had occurred as of January 1, 2014. The unaudited pro forma consolidated financial information is not necessarily indicative of what the Company's consolidated results of operations actually would have been had the acquisition been completed as of January 1, 2014. In addition, the unaudited pro forma consolidated financial information does not attempt to project the future results of operations of the Company combined with Scioderm. There were no revenues reported for Scioderm during the years ended December 31, 2015 and 2014. There were no nonrecurring adjustments in the pro forma Scioderm results for the year ended December 31, 2015. Year ended December 31, Unaudited Pro Forma Consolidated Information: 2015 2014 (in thousands) Revenue $ — $ Net loss Scioderm $ ) $ ) Net loss combined $ ) $ ) Acquisition of Callidus Biopharma, Inc. In November 2013, the Company acquired Callidus a privately-held biologics company focused on developing best-in-class ERTs for LSDs with its lead ERT ATB200 for Pompe disease in late preclinical development. The acquisition of the Callidus assets and technology complements Amicus' CHART™ platform for the development of next generation ERTs. In consideration for the merger, the Company agreed to issue an aggregate of 7.2 million shares of its common stock, par value $0.01 per share, to the former stockholders of Callidus. In addition, the Company will be obligated to make additional payments to the former stockholders of Callidus upon the achievement by the Company of certain clinical milestones of up to $35 million and regulatory approval milestones of up to $105 million as set forth in the Merger Agreement, provided that the aggregate consideration shall not exceed $130 million. The Company may, at its election, satisfy certain milestone payments identified in the Merger Agreement aggregating $40 million in shares of its Common Stock (calculated based on a price per share equal to the average of the last closing bid price per share for the Common Stock on The NASDAQ Global Select Market for the ten (10) trading days immediately preceding the date of payment). The milestone payments not permitted to be satisfied in Common Stock (as well as any payments that the Company is permitted to, but chooses not to, satisfy in Common Stock), as a result of the terms of the Merger Agreement, the rules of The NASDAQ Global Select Market, or otherwise, will be paid in cash. The fair value of the contingent acquisition consideration payments on the acquisition date was $10.6 million and was estimated by applying a probability-based income approach utilizing an appropriate discount rate. This estimation was based on significant inputs that are not observable in the market, referred to as Level 3 inputs. As of December 31, 2015, the range of outcomes and assumptions used to develop these estimates has changed to better reflect the probability of certain milestone outcomes. (see "— Note 10. Assets and Liabilities Measured at Fair Value", for additional discussion regarding fair value measurements of the contingent acquisition consideration payable). The Company determined the fair value of the contingent consideration to be $16.3 million at December 31, 2015, of which $5.6 million is payable in the next twelve months, resulting in an increase in the contingent consideration payable and related expense of $5.6 million year ended December 31, 2015. The expense is recorded as part of operating expense in the Consolidated Statement of Operations. For further information, see "— Note 4. Goodwill and Intangible Assets."

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets
Goodwill and Intangible Assets	4. Goodwill and Intangible Assets In connection with the acquisitions discussed in "— Note 3. Acquisitions, the Company has recognized goodwill of $197.8 million. The following table represents the changes in goodwill for the year ended December 31, 2015: (in millions) Balance at December 31, 2014 $ Goodwill related to Scioderm on date of acquisition (See Note 3) ​ ​ ​ ​ ​ Balance at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In connection with the acquisitions discussed in "— Note 3. Acquisitions," the Company recognized IPR&D of $486.7 million. Intangible assets related to IPR&D assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. During the period the assets are considered indefinite-lived, they will not be amortized but will be tested for impairment on an annual basis and between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate a reduction in the fair value of the IPR&D assets below their respective carrying amounts. The following table represents the changes in IPR&D for the year ended December 31, 2015: (in millions) Balance at December 31, 2014 $ IPR&D related to Scioderm on date of acquisition (See Note 3) ​ ​ ​ ​ ​ Balance at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During the 2015 impairment assessment, it was determined that the goodwill and intangible assets had not been impaired. Goodwill and intangible assets were assessed annually for impairment on October 1 and whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. If it is determined that the full carrying amount of an asset is not recoverable, an impairment loss is recorded in the amount by which the carrying amount of the asset exceeds its fair value. During the 2015 impairment assessment, it was determined that the goodwill and intangible assets had not been impaired thus there were no impairment changes to the balances in 2015.

Cash, Money Market Funds and Ma

Cash, Money Market Funds and Marketable Securities	12 Months Ended
	Dec. 31, 2015
Cash, Money Market Funds and Marketable Securities
Cash, Money Market Funds and Marketable Securities	5. Cash, Money Market Funds and Marketable Securities As of December 31, 2015, the Company held $69.5 million in cash and cash equivalents and $144.5 million of available-for-sale 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. Investments that have original maturities or greater than 3 months but less than 1 year are classified as short-term and investments with maturities that are greater than 1 year are classified as long-term. Cash and available for sale securities consisted of the following as of December 31, 2015 and December 31, 2014 (in thousands): As of December 31, 2015 Cost Unrealized Gain Unrealized Loss Fair Value Cash balances $ $ — $ — $ Corporate debt securities, current portion ) Commercial paper — Certificate of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Included in cash and cash equivalents $ $ — $ — $ Included in marketable securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and marketable securities $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2014 Cost Unrealized Gain Unrealized Loss Fair Value Cash balances $ $ — $ — $ Corporate debt securities, current portion — ) Corporate debt securities, non-current portion — ) Commercial paper — Certificate of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Included in cash and cash equivalents $ $ — $ — $ Included in marketable securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and marketable securities $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains and losses are reported as a component of other comprehensive gain/(loss) in the statements of comprehensive loss. For the year ended December 31, 2015 and 2014, unrealized holding gain of $17 thousand and unrealized holding loss of $132 thousand respectively, were included in the statements of comprehensive loss. For the years ended December 31, 2015 and 2014, 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, 2015 and December 31, 2014 reflect temporary impairments that have been in a loss position for less than twelve months and as such are recognized in other comprehensive gain/ (loss). The fair value of these available for sale securities in unrealized loss positions was $118.5 million and $129.2 million as of December 31, 2015 and 2014, 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 years ended December 31, 2015 and 2014, were as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance, beginning $ ) $ $ Current period changes in fair value, ) ) Reclassification of earnings, — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, ending $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property and Equipment
Property and Equipment	6. Property and Equipment Property and equipment consist of the following (in thousands): December 31, 2015 2014 Property and equipment consist of the following: Computer equipment $ $ Computer software Research equipment Furniture and fixtures Leasehold improvements ​ ​ ​ ​ ​ ​ ​ ​ Less accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation and amortization expense was $1.8 million and $1.5 million for the years ended December 31, 2015 and 2014, respectively. There were no capital lease obligations outstanding as of December 31, 2015.

Accounts Payable, Accrued Expen

Accounts Payable, Accrued Expenses and Long-Term Liabilities	12 Months Ended
	Dec. 31, 2015
Accounts Payable, Accrued Expenses and Long-Term Liabilities
Accounts Payable, Accrued Expenses And Long-Term Liabilities	7. Accounts Payable, Accrued Expenses and Long-Term Liabilities Accounts payable and accrued expenses consist of the following (in thousands): December 31, 2015 2014 Accounts payable $ $ Accrued professional fees Accrued contract manufacturing & contract research costs Accrued compensation and benefits Accrued facility costs Contingent success fee payable — Accrued other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other long-term liabilities consist of the following (in thousands): December 31, 2015 2014 Exit fees $ — $ Employee compensation and benefits Security deposits ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Related Party Transaction

Related Party Transaction	12 Months Ended
	Dec. 31, 2015
Related Party Transaction
Related Party Transaction	Note 8. Related Party Transaction In October 2015, the Company entered into the October 2015 Purchase Agreement with Redmile Capital Fund, LP and certain of its affiliates (collectively, "Redmile"). The Company received the proceeds related to the arrangement of $50.0 million cash and has recorded this liability on the balance sheet as "Due to related party" as of December 31, 2015, after the related debt discount. See "— Note 16. Short-Term Borrowings and Long-Term Debt" for more details on this transaction. As of December 31, 2015, Redmile beneficially owned approximately 6.7% of the Company's outstanding shares of common stock. On February 19, 2016, the Company entered into a Note and Warrant Purchase Agreement (the "February 2016 Purchase Agreement") with Redmile for an aggregate amount of up to $75.0 million. The Company has agreed with Redmile that in full consideration of the purchase price for the notes issued under the October 2015 Purchase Agreement, Redmile surrendered for cancellation all notes and warrants acquired from the October 2015 Purchase Agreement and the Company will pay Redmile any unpaid interest accrued thereunder. For additional information, see "— Note 20. Subsequent Events."

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity
Stockholders' Equity	Note 9. Stockholders' Equity Common Stock and Warrants As of December 31, 2015, the Company was authorized to issue 250 million shares of common stock. Dividends on common stock will be paid when, and if, declared by the board of directors. Each holder of common stock is entitled to vote on all matters that are appropriate for stockholder voting and is entitled to one vote for each share held. On February 26, 2016, the Company entered into a Sales Agreement with Cowen and Company, LLC ("Cowen") to create an at-the-market equity program under which the Company from time to time may offer and sell shares of its common stock, par value $0.01 per share, having an aggregate offering price of up to $100 million through Cowen (the "ATM Facility"). The ATM Facility will not become effective until after the Company files a new registration statement with the SEC covering the securities to be offered through the ATM Facility. In October 2015, the Company entered into a note and warrant purchase agreement (the "October 2015 Purchase Agreement") with Redmile, whereby it sold, on a private placement basis, (a) $50.0 million aggregate principal amount of its unsecured promissory notes ("Notes") and (b) five-year warrants ("Warrants") for 1.3 million shares of Common Stock. The Company evaluated the warrants against current accounting guidance and determined that these warrants should be accounted as a component of equity. As such, these warrants are valued at issuance date using the Black-Scholes valuation model using the following six inputs: (1) the closing price of Amicus stock on the day of evaluation of $13.75; (2) the exercise price of the warrants of $16.84; (3) the remaining term of the warrants of 5 years; (4) the volatility of Amicus' stock for the five year term of 75.1%; (5) the annual rate of dividends of 0%; and (6) the risk-free rate of return of 1.37%. The Black Scholes value of the warrants was $10.6 million with a relative fair value of $8.8 million. On February 19, 2016, the Company entered into a Note and Warrant Purchase Agreement (the "February 2016 Purchase Agreement") with Redmile for an aggregate amount of up to $75.0 million. The Company has agreed with Redmile that in full consideration of the purchase price for the notes issued under the October 2015 Purchase Agreement, Redmile surrendered for cancellation all notes and warrants acquired from the October 2015 Purchase Agreement and the Company will pay Redmile any unpaid interest accrued thereunder. For additional information, see "—Note 20. Subsequent Events." In September 2015, the Company acquired Scioderm with cash and stock. As part of the acquisition, the Company paid holders of Scioderm an amount equal to $223.9 million, of which approximately $141.1 million was paid in cash and approximately $82.8 million was paid through the issuance of 5.9 million newly issued shares. The Company agreed to pay up to an additional $361 million upon achievement of certain clinical and regulatory milestones, and $257 million to Scioderm shareholders, option holders, and warrant holders upon achievement of certain sales milestones. In June 2015, the Company issued a total of 19.5 million shares through a public offering at a price of $13.25 per share, with net proceeds of $243.0 million. The Company expects to use the net proceeds of the offering for investment in the global commercialization infrastructure for Galafold for Fabry disease, the continued clinical development of its product candidates and for other general corporate purposes. In November 2014, we sold a total of 15.9 million shares of our common stock, par value $0.01 per share, at a public offering price of $6.50 per share. The aggregate offering proceeds were approximately $97.2 million. In July 2014, the Company completed a $40 million at the market ("ATM") equity offering under which the Company sold shares of its common stock, par value $0.01 per shares with Cowen and Company LLC as sales agent. Under the ATM equity program the Company sold 14.3 million shares of common stock resulting in net proceeds of $38.6 million. Nonqualified Cash Plan In July 2014, the Board of Directors approved the Company's Deferral Plan, (the "Deferral Plan") that provides certain key employees and members of the Board of Directors as selected by the Compensation Committee, with an opportunity to defer the receipt of such participant's base salary, bonus and director's fees, as applicable. The Deferral Plan is intended to be a nonqualified deferred compensation plan that complies with the provisions of Section 409A of the Internal Revenue Code of 1986 as amended. Deferred compensation amounts under the Deferral Plan as of December 31, 2015 were approximately $0.7 million, as compared to $0.1 million on December 31, 2014 and are included in other long-term liabilities. Deferral Plan assets as of December 31, 2015 were $0.7 million and are classified as trading securities. The Deferred Plan assets are recorded at fair value with changes in the investments' fair value recognized in the period they occur. During the year ended December 31, 2015, income from the investments was $17 thousand and unrealized loss was $50 thousand. Equity Incentive Plan In June 2014, the Company's stockholders approved the Amended and Restated 2007 Equity Incentive Plan (the "Plan"). The amendment to the Plan makes an additional 6 million shares of the Company's common stock available for issuance and increases the maximum number of shares within the Plan that may be issued as restricted stock, RSUs, stock grants and any other similar awards from 1.1 million to 1.5 million shares. As of December 31, 2015, awards issued under the Plan include both stock options and RSUs. In May 2007, the Company's Board of Directors and stockholders approved the Company's 2007 Director Option Plan (the "2007 Director Plan"). The Plan provides for the granting of restricted stock and options to purchase common stock in the Company to employees, advisors and consultants at a price to be determined by the Company's board of directors. The Plan is intended to encourage ownership of stock by employees and consultants of the Company and to provide additional incentives for them to promote the success of the Company's business. The 2007 Director Plan is intended to promote the recruiting and retention of highly qualified eligible directors and strengthen the commonality of interest between directors and stockholders by encouraging ownership of common stock of the Company. Under the provisions of each plan, no option will have a term in excess of 10 years. The Board of Directors, or its committee, is responsible for determining the individuals to be granted options, the number of options each individual will receive, the option price per share, and the exercise period of each option. Options granted pursuant to the Plan generally vest 25% on the first year anniversary date of grant plus an additional 1/48th for each month thereafter and may be exercised in whole or in part for 100% of the shares vested at any time after the date of grant. Options under the 2007 Director Plan may be granted to new directors upon joining the Board and vest in the same manner as options under the Plan. In addition, options are automatically granted to all directors at each annual meeting of stockholders and vest on the date of the annual meeting of stockholders of the Company in the year following the year during which the options were granted. As of December 31, 2015, the Company has reserved up to 2,551,120 shares for issuance under the Plan and the 2007 Director Plan. Stock Option Grants The Company adopted the fair value method of measuring stock-based compensation, using the fair value of each equity award granted. The Company chose the "straight-line" attribution method for allocating compensation costs and recognized the fair value of each stock option on a straight-line basis over the vesting period of the related awards. The Company uses the Black-Scholes option pricing model when estimating the grant date fair value for stock-based awards. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs. Expected volatility was based on our historical volatility since our initial public offering in May 2007.The average expected life was determined using the "simplified" method of estimating the expected exercise term which is the mid-point between the vesting date and the end of the contractual term. As the Company's stock price volatility has been over 75% and it has experienced significant business transactions, the Company does not have sufficient reliable exercise data in order to justify a change in the use of the "simplified" method of estimating the expected exercise term of employee stock option grants. The risk-free interest rate is based on U.S. Treasury, zero-coupon issues with a remaining term equal to the expected life assumed at the date of grant. Forfeitures are estimated based on voluntary termination behavior, as well as a historical analysis of actual option forfeitures. The weighted average assumptions used in the Black-Scholes option pricing model are as follows: Years Ended December 31, 2015 2014 2013 Expected stock price volatility % % % Risk free interest rate % % % Expected life of options (years) Expected annual dividend per share $ $ $ The weighted average grant-date fair value per share of options granted during 2015, 2014 and 2013 were $7.51, $2.12 and $2.14, respectively. The following table summarizes information about stock options outstanding: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life Aggregate Intrinsic Value (in thousands) (in millions) Options outstanding, December 31, 2012 $ Granted $ Exercised — — Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2013 $ Granted $ Exercised ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2014 $ Granted $ Exercised ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2015 $ 7.3 years $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested and unvested expected to vest, December 31, 2015 $ 7.2 years $ Exercisable at December 31, 2015 $ 5.7 years $ The aggregate intrinsic value of options exercised during the years ended December 31, 2015 and 2014 was $14.7 million and $2.8 million, respectively. There were no options exercised during the year ended December 31, 2013. Cash proceeds from stock options exercised during the years ended December 31, 2015 and 2014 were $11.2 million and $3.7 million respectively. As of December 31, 2015, the total unrecognized compensation cost related to non-vested stock options granted was $24.6 million and is expected to be recognized over a weighted average period of 3.1 years. Restricted Stock Units In April 2014, the Compensation Committee made awards of RSUs to certain employees of the Company. The RSUs awarded under the Plan are generally subject to graded vesting and are contingent on such employee's continued service on such date. RSUs are generally subject to forfeiture if employment terminates prior to the release of vesting restrictions. The Company expenses the cost of the RSUs, which is determined to be the fair market value of the shares of common stock underlying the RSUs at the date of grant, ratably over the period during which the vesting restrictions lapse. A summary of non-vested RSU activity under the Plan for the year ended December 31, 2015 is as follows: Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Years Aggregate Intrinsic Value (in thousands) (in millions) Non-vested units as of December 31, 2014 $ Granted $ Vested ) $ — Forfeited — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested units as of December 31 ,2015 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the year ended December 31, 2015, 0.8 million of the RSUs vested and all non-vested units are expected to vest over their normal term. As of December 31, 2015, there was $4.0 million of total unrecognized compensation cost related to unvested RSUs with service-based vesting conditions. These costs are expected to be recognized over a weighted average period of 0.5 years. In April 2014, the Board of Directors approved the Company's Restricted Stock Unit Deferral Plan ("the Deferred Compensation Plan"), which provides selected employees with an opportunity to defer receipt of RSUs until the first to occur of termination of the employee's employment or a date selected by the employee. Any RSUs deferred under the Deferred Compensation Plan would be fully vested once the original vesting conditions of the RSU were satisfied. Compensation Expense Related to Equity Awards The following table summarizes the stock-based compensation expense recognized in the statements of operations (in thousands): Years Ended December 31, 2015 2014 2013 Stock compensation expense recognized in: Research and development expense $ $ $ General and administrative expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stock compensation expense $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value	12 Months Ended
	Dec. 31, 2015
Assets and Liabilities Measured at Fair Value
Assets and Liabilities Measured at Fair Value	10. 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 year ended December 31, 2015. No transfers of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the year ended December 31, 2015. Success Fee Payable In connection with the Term Loan, as disclosed in "— Note 16. Short Term Borrowings and Long Term Debt," the Company recorded a contingent liability of $0.4 million related to a success fee payable within six months of trigger event, with the trigger event being regulatory acceptance of NDA or MAA submission. The success fee payable to the lender was probability adjusted and discounted utilizing an appropriate discount rate and hence classified as Level 3. In June 2015, EMA validated the submission of the Company's MAA and the success fee became payable. The Company paid the success fee in connection with the re-payment of the debt in June 2015. Note Payable to Related Party In connection with the notes payable to Redmile Capital Fund, LP and certain of its associates, as disclosed in "— Note 16. Short Term Borrowings and Long Term Debt", and Warrants as disclosed in "— Note 9. Stockholders' Equity," the Company recorded the notes as a liability at $50 million. Due to the embedded redemption (put and/or call) features in the note agreement, it was determined that the fair value of the warrants should be bifurcated from the value of the notes payable and recorded as a debt discount. The debt discount is to be amortized over the life of the notes. The relative fair value of the warrants and the debt discount was determined to be $8.8 million with amortization expense of $0.4 million for the year ended December 31, 2015. The net carrying value of the notes at December 31, 2015 was $41.6 million. The Company evaluated the warrants against current accounting guidance and determined that the related warrants should be accounted as a component of equity. As such, these warrants are valued at issuance date using the Black-Scholes valuation model using the following six inputs: (1) the closing price of Amicus stock on the day of evaluation of $13.75; (2) the exercise price of the warrants of $16.84; (3) the remaining term of the warrants of 5 years; (4) the volatility of Amicus' stock for the five year term of 75.1%; (5) the annual rate of dividends of 0%; and (6) the risk-free rate of return of 1.37%.The resulting Black Scholes value of the warrants was $10.6 million and the relative fair value was determined to be $8.8 million. Contingent Consideration Payable The contingent consideration payable resulted from acquisition of Scioderm and Callidus, as discussed in "— Note 3. Acquisitions." Our most recent valuation was determined using a probability weighted discounted cash flow valuation approach. Using this approach, expected future cash flows are calculated over the expected life of the agreement, are discounted, and then exercise scenario probabilities are applied. The valuation will be performed quarterly. Gains and losses are included in the statement of operations. The contingent consideration payable has been classified as a Level 3 liability as its valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the various inputs to the valuation approach the estimated fair value could be significantly higher or lower than the fair value the Company determined. The Company may be required to record losses in future periods. The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Scioderm: Contingent Consideration Liability Fair value as of December 31, 2015 Valuation Technique Unobservable Input Range Discount rate 0.7% - 1.5% Clinical and regulatory milestones $236.7 million Probability weighted discounted cash flow Probability of achievement of milestones 66.5% - 70% Projected year of payments 2016 - 2019 Revenue volatility 58% Revenue-based milestones $21.1 million Monte Carlo Discount rate 1.3% - 2.4% Projected year of payments 2018 - 2028 The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Callidus: Contingent Consideration Liability Fair value as of December 31, 2015 Valuation Technique Unobservable Input Range Discount rate 11.5% Clinical and regulatory milestones $16.3 million Probability weighted discounted cash flow Probability of achievement of milestones 30% - 95% Projected year of payments 2016 - 2026 Contingent consideration liabilities are remeasured to fair value each reporting period using projected revenues, discount rates, probabilities of payment and projected payment dates. Projected contingent payment amounts related to clinical and regulatory based milestones are discounted back to the current period using a discounted cash flow model. Revenue-based payments are valued using a monte-carlo valuation model, which simulates future revenues during the earn out-period using management's best estimates. Projected revenues are based on our most recent internal operational budgets and long-range strategic plans. Increases in projected revenues and probabilities of payment may result in higher fair value measurements. Increases in discount rates and the time to payment may result in lower fair value measurements. Increases or decreases in any of those inputs together, or in isolation, may result in a significantly lower or higher fair value measurement. There is no assurance that any of the conditions for the milestone payments will be met. The following table shows the change in the balance of contingent consideration payable for the year ended December 31, 2015, 2014 and 2013, respectively: Year ended December 31, 2015 2014 Balance, beginning of the period $ $ Additions, from business acquisitions — Unrealized change in fair value change during the period, included in Statement of Operations ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of the period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred Compensation Plan-Investment and Liability As disclosed in "— Note 9. Stockholders' Equity," the Deferral Plan provides certain key employees and members of the Board of Directors with an opportunity to defer the receipt of such participant's base salary, bonus and director's fees, as applicable. Deferral Plan assets as of December 31, 2015 were $0.7 million, are classified as trading securities and recorded at fair value with changes in the investments' fair value recognized in the period they occur. The asset investments consist of market exchanged mutual funds. During the year ended December 31, 2015, the interest income was $17 thousand and the unrealized loss was $50 thousand. The Company considers its investments in marketable securities, as available-for-sale and classifies these assets and related liability within the fair value hierarchy as Level 2 primarily utilizing broker quotes in a non-active market for valuation of these securities. A summary of the fair value of the Company's recurring assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2015 are identified in the following table (in thousands): Level 1 Level 2 Total Assets: Cash/money market funds $ $ — $ Commercial paper — Corporate debt securities — Certificate of deposit — Deferred compensation plan assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2 Level 3 Total Liabilities: Contingent consideration payable $ — $ $ Deferred compensation plan liability — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following is a summary of the Company's non-recurring liability aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2015 are identified in the following table (in thousands): Level 3 Liabilities: Note payable to related party $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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, 2014 are identified in the following table (in thousands): Level 1 Level 2 Total Assets: Cash/money market funds $ $ — $ Commercial paper — Corporate debt securities — Certificate of deposit — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2 Level 3 Total Liabilities: Contingent success fee payable — Contingent consideration payable — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ — $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2015
401(k) Plan
401(k) Plan	11. 401(k) Plan The Company has a 401(k) plan (the "401(k) Plan") covering all eligible employees and provides for a company match of up to 5% of salary and bonus paid during the year. The Company's vesting policy is that the Company match vests immediately upon enrollment. There were no changes to the policy in 2014 or 2015. The Company's total contribution to the 401(k) Plan was $0.9 million, $0.6 million and $0.7 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2015
Leases
Leases	12. Leases Operating Leases The Company currently leases office space and research laboratory space in various facilities under operating agreements expiring at various dates through 2025. The following table contains information about our current significant leased properties as of December 31, 2015: Location Approximate Square Feet Use Lease expiry date Cranbury, New Jersey Office and laboratory September 2025 San Diego, California Office and laboratory September 2016 Durham, North Carolina Office and laboratory June 2016 Buckinghamshire, United Kingdom Office September 2020 Munich, Germany Office April 2017 In addition to the above, we also maintain small offices in the Netherlands, Spain and France. The facility at San Diego, California, was closed as part of the restructuring process in December 2013 and in May 2014, the Company entered into a sublease agreement with a tenant for the remainder of our original lease term for the San Diego, California facility. We believe that our current office and laboratory facilities are adequate and suitable for our current and anticipated needs. We believe that, to the extent required, we will be able to lease or buy additional facilities at commercially reasonable rates. Rent expenses for the Company's facilities are recognized over the term of the lease. The Company recognizes rent starting when possession of the facility is taken from the landlord. When a lease contains a predetermined fixed escalation of the minimum rent, the Company recognizes the related rent expense on a straight-line basis and records the difference between the recognized rental expense and the amounts payable under the lease as deferred rent liability. Tenant leasehold improvement allowances are reflected in accrued expenses on the consolidated balance sheets and are amortized as a reduction to rent expense in the statement of operations over the term of the lease. At December 31, 2015, aggregate annual future minimum lease payments, net of income from subleases, under these leases are as follows: (in thousands) 2016 2017 2018 2019 2020 and beyond Total Minimum lease payments $ $ $ $ $ $ Less: income from sublease ) — — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net minimum lease payments $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Rent expense for the years ended December 31, 2015, 2014 and 2013 were $2.6 million, $2.4 million and $2.6 million respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes
Income Taxes	13. Income Taxes In June 2006, the FASB issued a single model to address accounting for uncertainty in tax positions. The model clarifies the accounting for income taxes, by prescribing a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. It also provides guidance on de-recognition, measurement, and classification of amounts relating to uncertain tax positions, accounting for and disclosure of interest and penalties, accounting in interim periods and disclosures required. The Company adopted the FASB requirements as of January 1, 2007 and determined that it did not have a material impact on the Company's financial position and results of operations. The Company did not recognize interest or penalties related to income tax during the period ended December 31, 2015 and did not accrue for interest or penalties as of December 31, 2015. The Company does not have an accrual for uncertain tax positions as of December 31, 2015. Tax returns for all years 2008 and thereafter are subject to future examination by tax authorities. Deferred income taxes reflect the net effect of temporary difference between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of the deferred tax assets and liabilities are as follows (in thousands): For Years Ended December 31, 2015 2014 Non-current deferred tax assets Amortization/depreciation $ $ Research tax credit Net operating loss carry forwards Deferred revenue Non-cash stock issue $ $ Others ​ ​ ​ ​ ​ ​ ​ ​ Gross deferred tax assets Deferred tax liability related to business acquisition ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred tax asset Less valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets (liability) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company records a valuation allowance for temporary differences for which it is more likely than not that the Company will not receive future tax benefits. At December 31, 2015, and 2014, the Company recorded valuation allowances of $148.4 million and $213.7 million, respectively, representing an increase in the valuation allowance of $26.8 million in 2014 and an increase of $65.3 million in 2015, due to the uncertainty regarding the realization of such deferred tax assets, to offset the benefits of net operating losses generated during those years. The deferred tax liability related to business acquisitions pertains to the basis difference in IPR&D acquired by the Company. The Company's policy is to record a deferred tax liability related to acquired IPR&D that may eventually be realized either upon amortization of the asset when the research is completed and a product is successfully launched or the write-off of the asset if it is abandoned or unsuccessful. As of December 31, 2015, the Company had federal, state and foreign net operating loss carry forwards ("NOLs") of approximately $402.2 million, $378.8 million and $8.3 million, respectively. The federal carry forward will expire in 2028 through 2035. Most of the state carry forwards generated prior to 2009 have expired through 2015. The remaining state carry forwards including those generated in 2009 through 2015 will expire in 2029 through 2035 due to a change in the New Jersey state law regarding the net operating loss carry forward period. Utilization of NOLs may be subject to a substantial limitation pursuant to Section 382 of the Code as well as similar state statutes in the event of an ownership change. Such ownership changes have occurred in the past, and could occur again in the future As a result of these ownership changes, Section 382 places an annual limitation on the amount of NOLs that can be utilized to offset future taxable income each year, which is based on the value of the company at the change date. This limitation could result in expiration of those carry forwards before utilization. In general, an ownership change, as defined by Section 382, results from transactions that increase the ownership of certain stockholders or public groups in the stock of a corporation by more than 50 percentage points over a three year period. The Company completed a detailed study of its cumulative ownership changes for 2015 and determined that in 2015, there was no ownership change in excess of 50%; therefore there was no write-down to net realizable value of the federal NOLs and research and development credits subject to the 382 limitations. A tax benefit of $3.6 million associated with the exercise of stock options will be recorded in additional paid-in capital when the associated net operating loss is recognized. For financial reporting purposes, income (loss) before income taxes includes the following components (in thousands): Years Ended December 31, 2015 2014 2013 United States $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 31, 2015, 2014 and 2013 are as follows: Years Ended December 31, 2015 2014 2013 Statutory rate )% )% )% State taxes, net of federal benefit ) ) ) Permanent adjustments ) R&D credit ) ) ) Foreign income tax rate differential — — Other — Valuation allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net )% )% )% ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company recognized a tax benefit of $1.1 million and $3.5 million in connection with the sale of net operating losses and research and development credits in the New Jersey Transfer Program for the years ended December 31, 2014 and 2013, respectively. There were no sales of net operating losses and research and development credits for the year ended December 31, 2015.

Licenses

Licenses	12 Months Ended
	Dec. 31, 2015
Licenses
Licenses	14. Licenses The Company acquired rights to develop and commercialize its product candidates through licenses granted by various parties. The following summarizes the Company's material rights and obligations under those licenses: GSK — For discussion of the royalties and milestone payments potentially due to GSK, see "— Note 15. Collaborative Agreements." Mt. Sinai School of Medicine of New York University ("MSSM") — The Company acquired exclusive worldwide patent rights to develop and commercialize migalastat and other pharmacological chaperones for the prevention or treatment of human diseases or clinical conditions by increasing the activity of wild-type and mutant enzymes pursuant to a license agreement with MSSM. This agreement expires upon expiration of the last of the licensed patent rights, which will be in 2019, subject to any patent term extension that may be granted, or 2024 if the Company develops a product for combination therapy (pharmacological chaperone plus ERT) and a patent issues from the pending application covering combination therapy, subject to any patent term extension that may be granted. Under this agreement, to date the Company has paid no upfront or annual license fees and has no milestone or future payments other than royalties on net sales. Under its license agreements, if the Company owes royalties on net sales for one of its products to more than one of the above licensors, then it has the right to reduce the royalties owed to one licensor for royalties paid to another. The amount of royalties to be offset is generally limited in each license and can vary under each agreement. For migalastat, the Company will owe royalties only to MSSM and will owe no milestone payments. The Company's rights with respect to these agreements to develop and commercialize migalastat may terminate, in whole or in part, if the Company fails to meet certain development or commercialization requirements or if the Company does not meet its obligations to make royalty payments.

Collaborative Agreements

Collaborative Agreements	12 Months Ended
	Dec. 31, 2015
Collaborative Agreements
Collaborative Agreements	15. Collaborative Agreements GSK In November 2013, Amicus entered into the Revised Agreement with GSK, pursuant to which Amicus has obtained global rights to develop and commercialize migalastat as a monotherapy and in combination with ERT for Fabry disease. The Revised Agreement amends and replaces in its entirety the Expanded Agreement entered into between Amicus and GSK in July 2012. Under the terms of the Revised Agreement, there was no upfront payment from Amicus to GSK. For migalastat monotherapy, GSK is eligible to receive post-approval and sales-based milestones up to $40 million, as well as tiered royalties in the mid-teens in eight major markets outside the U.S. Under the terms of the Revised Agreement, GSK will no longer jointly fund development costs for all formulations of migalastat. In evaluating the impact of both the Expanded Collaboration Agreement and the Revised 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 (i.e., 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 did not believe that, for accounting purposes, the new U.S. licensing rights to migalastat obtained from GSK under the Expanded Collaboration Agreement, nor the ex U.S. licensing rights to migalastat obtained from GSK under the Revised Agreement, represented a separate, identifiable benefit from the licenses in the Original Collaboration Agreement entered into between Amicus and GSK in 2010. The contingent amounts payable to GSK were 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 worldwide licensing rights to migalastat. 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 recognized 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 was also affected by the determination that the overall total arrangement consideration was no longer fixed and determinable, despite the fact that the research activities continued and that the research expense reimbursements by GSK to Amicus were received as the research activities related to the reimbursement had been completed. Therefore the research reimbursements from GSK were recorded as deferred reimbursements on the balance sheet and would not recognized until the total arrangement consideration becomes fixed and determinable. As a result, all revenue recognition was suspended until the total arrangement consideration would become fixed and determinable. In addition, future milestone payments made by the Company will be applied against the balance of this deferred reimbursements account. 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. Biogen In September 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 was responsible for funding all discovery, development, and commercialization activities. In addition the Company was reimbursed for all full-time employees working on the project as part of a cost sharing arrangement. The Company was 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. As the Company has not commenced its planned principal operations (i.e. selling commercial products) 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 December 31, 2014, the Company recognized $1.2 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 would be recognized as revenue in the period that the milestone was 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. In September 2014, the Company and Biogen concluded their research collaboration. The Company's most advanced Parkinson's candidate is AT3375, which was developed outside the collaboration and is wholly-owned by the Company.

Short-Term Borrowings and Long-

Short-Term Borrowings and Long-Term Debt	12 Months Ended
	Dec. 31, 2015
Short-Term Borrowings and Long-Term Debt
Short-Term Borrowings and Long-Term Debt	16. Short-Term Borrowings and Long-Term Debt In October 2015, the Company entered into a Note and Warrant Purchase Agreement (the "October 2015 Purchase Agreement") with Redmile Capital Fund, LP and certain of its affiliates, whereby it sold, on a private placement basis, (a) $50.0 million aggregate principal amount of its unsecured promissory notes ("Notes") and (b) five-year warrants ("Warrants") for 1.3 million shares of Common Stock. The payment terms under the purchase agreement contains two installments, the first $15.0 million in October 2017 and the balance $35.0 million in October 2020. Interest is payable at 4.1% on a monthly basis over the term of the loan. The promissory notes are recorded as due to related party on the Consolidated Balance Sheet. Due to the embedded redemption (put and/or call) features in the note agreement, it was determined that the fair value of the warrants should be bifurcated from the value of the notes payable and recorded as a debt discount. The debt discount is to be amortized over the life of the notes. The relative fair value of the warrants and the debt discount was determined to be $8.8 million with amortization expense of $0.4 million for the year ended December 31, 2015. The net carrying value of the notes at December 31, 2015 was $41.6 million. On February 19, 2016, the Company entered into a Note and Warrant Purchase Agreement (the "February 2016 Purchase Agreement") with Redmile for an aggregate amount of up to $75.0 million. The Company has agreed with Redmile that in full consideration of the purchase price for the notes issued under the October 2015 Purchase Agreement, Redmile surrendered for cancellation all notes and warrants acquired from the October 2015 Purchase Agreement and the Company will pay Redmile any unpaid interest accrued thereunder. For additional information, see " — Note 20. Subsequent Events." In December 2013, the Company entered into a credit and security agreement with a lending syndicate consisting of MidCap Funding III, LLC, Oxford Finance LLC, and Silicon Valley Bank ("SVB") which provided an aggregate of $25 million (the "Term Loan"). The Company drew $15 million of the aggregate principal amount which bore interest at a rate per annum fixed at 8.5%. The Company made interest-only payments on the Term Loan beginning January 1, 2014. In June 2015, the Company paid off the outstanding balance of the term loan and in connection with this repayment the Company also paid a $0.5 million exit fee and a $0.4 million success fee due to the successful acceptance of the MAA in June 2015. The net loss on extinguishment of the debt was $1.0 million and is included in the statement of operations for the year ended December 31, 2015. The carrying amount of the Company's borrowings approximates fair value at December 31, 2015. The remaining future minimum payments of principal due as of December 31, 2015 are as follows (in thousands): Years ending December 31: 2016 $ — 2017 2018 — 2019 — 2020 and beyond ​ ​ ​ ​ ​ Total principal obligation Less short-term portion (— ) ​ ​ ​ ​ ​ Long-term portion Less debt discount ) ​ ​ ​ ​ ​ Long term portion, net of debt discount $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2015
Restructuring Charges
Restructuring Charges	17. Restructuring Charges In December 2013, the Company initiated and completed a facilities consolidation effort, closing one of its leased locations in San Diego, CA. The Company recorded a total charge of $2.0 million during the fourth quarter of 2013 which included $1.2 million for employment termination costs payable and a facilities consolidation charge of $0.8 million consisting of lease payments of $0.7 million related to the net present value of the net future minimum lease payments at the cease-use date and the write-down of the net book value of the fixed assets in the vacated building of $0.1 million. During the year ended December 31, 2014, all of the restructuring charges related to employment termination costs were paid. The following table summarizes the restructuring charges and utilization for the year ended December 31, 2015 (in thousands): Balance as of December 31, 2014 Charges Cash Payments Adjustments Balance as of December 31, 2015 Facilities consolidation — ) The lease charges will be paid over the remaining lease term which expires in September 2016.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2015
Earnings per Share
Earnings per Share	18. Earnings per Share 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 (in thousands except share amounts): Years Ended December 31, 2015 2014 2013 Historical Numerator: Net loss attributable to common stockholders $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: Weighted average common shares outstanding — basic and diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive common stock equivalents would include the dilutive effect of common stock options, restricted stock units and warrants for common stock equivalents. Potentially dilutive common stock equivalents were excluded from the diluted earnings per share denominator for all periods because of their anti-dilutive effect. The table below presents potential shares of common stock that were excluded from the computation as they were anti-dilutive using the treasury stock method (in thousands): Year ended December 31, 2015 2014 2013 Options to purchase common stock Outstanding warrants, convertible to common stock Unvested restricted stock units — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total number of potentially issuable shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies.
Commitments and Contingencies	Note 19. Commitments and Contingencies Since October 1, 2015, three purported securities class action lawsuits have been commenced in the United States District Court for New Jersey, naming as defendants the Company, its Chairman and Chief Executive Officer, and in one of the actions, its Chief Medical Officer. The lawsuits allege violations of the Securities Exchange Act of 1934 in connection with allegedly false and misleading statements made by the Company related to the regulatory approval path for migalastat. The plaintiffs seek, among other things, damages for purchasers of the Company's common stock during different periods, all of which fall between March 19, 2015 and October 1, 2015. It is possible that additional suits will be filed, or allegations received from stockholders, with respect to similar matters and also naming the Company and/or its officers and directors as defendants. The Company anticipates that these lawsuits will be consolidated into a consolidated action. On or about November 2, 2015, a derivative lawsuit was filed by an Amicus shareholder purportedly on Amicus' behalf in the Superior Court of New Jersey, Middlesex County, Chancery Division. Defendants are the individuals who serve on the Amicus Board of Directors. Amicus itself is named as a nominal defendant. Filed shortly after the three purported securities class action lawsuits described above, the derivative lawsuit alleges claims for breach of state law fiduciary duties, waste of corporate assets, and unjust enrichment based on alleged violations of the Securities Exchange Act of 1934, in connection with allegedly false and misleading statements made by Amicus related to the regulatory approval path for migalastat HCl. The plaintiff seeks, among other things, to require the Amicus Board to take certain actions to reform its corporate governance procedures, including greater shareholder input and a provision to permit shareholders to nominate candidates for election to the Board, along with restitution, costs of suit and attorney's fees. These lawsuit and any other related lawsuits are subject to inherent uncertainties and the actual cost will depend upon many unknown factors. The outcome of the litigation is necessarily uncertain and the Company could be forced to expend significant resources in the defense of these suits, and the Company may not prevail. The Company is not currently able to estimate the possible cost to it from this matter, as these lawsuits are currently at an early stage and the Company cannot ascertain how long it may take to resolve this matter. The Company believes that it has meritorious defenses and intends to defend this lawsuit vigorously.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events
Subsequent Events	20. Subsequent Events On February 19, 2016, the Company entered into the "February 2016 Purchase Agreement" with Redmile, whereby it sold, on a private placement basis, (a) $75.0 million aggregate principal amount of its unsecured promissory notes of which $50.0 million becomes available immediately and the balance $25.0 million becomes available subject to certain conditions and (b) 1.9 million warrants that have a term of five-years. The payment terms under the purchase agreement contains two installments, the first $15.0 million in October 2017 and the balance $35.0 million in October 2021. For each tranche, interest will accrue at 3.875% but go unpaid until final maturity. The Company has agreed with Redmile that in full consideration of the purchase price for the notes issued under the October 2015 Purchase Agreement, Redmile surrendered for cancellation all notes and warrants acquired from the October 2015 Purchase Agreement and the Company will pay Redmile any unpaid interest accrued thereunder. The Company is in the process of evaluating the accounting treatment for the debt and the warrants. On February 26, 2016, the Company entered into a Sales Agreement with Cowen and Company, LLC ("Cowen") to create an at-the-market equity program under which the Company from time to time may offer and sell shares of its common stock, par value $0.01 per share, having an aggregate offering price of up to $100 million through Cowen (the "ATM Facility"). The ATM Facility will not become effective until after the Company files a new registration statement with the SEC covering the securities to be offered through the ATM Facility.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited - in thousands except per share data)	12 Months Ended
	Dec. 31, 2015
Selected Quarterly Financial Data (Unaudited - in thousands except per share data)
Selected Quarterly Financial Data (Unaudited - in thousands except per share data)	21. Selected Quarterly Financial Data (Unaudited — in thousands except per share data) Quarters Ended March 31 June 30 September 30 December 31 2015 Net loss $ ) $ ) $ ) $ ) Basic and diluted net loss per common share (1) ) ) ) ) 2014 Net loss $ ) $ ) $ ) $ ) Basic and diluted net loss per common share (1) ) ) ) ) (1) Per common share amounts for the quarters and full years have been calculated separately. Accordingly, quarterly amounts do not add to the annual amounts because of differences on the weighted-average common shares outstanding during each period principally due to the effect of the Company issuing shares of its common stock during the year.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented.
Consolidation	Consolidation The financial statements include the accounts of Amicus Therapeutics, Inc. and its wholly owned subsidiaries, Amicus Therapeutics UK Limited, Scioderm, Inc., Callidus Biopharma, Inc. Amicus Therapeutics UK Limited includes Amicus Therapeutics SAS, Amicus Therapeutics B.V, Amicus Therapeutics GmbH, and Amicus Therapeutics S.r.l. All significant intercompany transactions and balances are eliminated in consolidation. These subsidiaries are not material to the overall financial statements of the Company.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S.GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.
Cash, Money Market Funds, and Marketable Securities	Cash, Money Market Funds, and Marketable Securities The Company considers all highly liquid investments purchased with a maturity of three months or less at the date of acquisition, to be cash equivalents. Marketable securities consist of fixed income investments with a maturity of greater than three months and other highly liquid investments that can be readily purchased or sold using established markets. These investments are classified as available-for-sale and are reported at fair value on the Company's balance sheet. Unrealized holding gains and losses are reported within comprehensive income/ (loss) in the statements of comprehensive loss. Fair value is based on available market information including quoted market prices, broker or dealer quotations or other observable inputs. See "— Note 5. Cash, Money Market Funds and Marketable Securities", for a summary of available-for-sale securities as of December 31, 2015 and 2014.
Concentration of Credit Risk	Concentration of Credit Risk The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company maintains its cash and cash equivalents in bank accounts, which, at times, exceed federally insured limits. The Company invests its marketable securities in high-quality commercial financial instruments. The Company has not recognized any losses from credit risks on such accounts during any of the periods presented. The Company believes it is not exposed to significant credit risk on cash and cash equivalents or its marketable securities.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is calculated over the estimated useful lives of the respective assets, which range from three to five years, or the lesser of the related initial term of the lease or useful life for leasehold improvements. The initial cost of property and equipment consists of its purchase price and any directly attributable costs of bringing the asset to its working condition and location for its intended use. Expenditures incurred after the fixed assets have been put into operation, such as repairs and maintenance, are charged to income in the period in which the costs are incurred. Major replacements, improvements and additions are capitalized in accordance with Company policy.
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 where the last deliverable within the single unit of accounting is expected to be delivered. The Company's current revenue recognition policies 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: · 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 evaluate if 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. The reimbursements for research and development costs under collaboration agreements that meet the criteria for revenue recognition are included in Research Revenue and the costs associated with these reimbursable amounts are included in research and development expenses. 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 is 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.
Contingent Liabilities	Contingent Liabilities On an ongoing basis, the Company may be involved in various claims, and legal proceedings. On a quarterly basis, the Company reviews the status of each significant matter and assesses its potential financial exposure. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, the Company will accrue a liability for the estimated loss. Because of uncertainties related to claims and litigation, accruals will be based on our best estimates based on available information. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation or settlement of claims, the Company may reassess the potential liability related to these matters and may revise these estimates, which could result in a material adverse adjustments to the Company's operating results.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expense consists primarily of costs related to personnel, including salaries and other personnel related expenses, consulting fees and the cost of facilities and support services used in drug development. Assets acquired that are used for research and development and have no future alternative use are expensed as in-process research and development.
Interest Income and Interest Expense	Interest Income and Interest Expense Interest income consists of interest earned on the Company's cash and cash equivalents and marketable securities. Interest expense consists of interest incurred on capital leases and secured debt.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method. Under this method deferred income tax liabilities and assets are determined based on the difference between the financial statement carrying amounts and tax basis of assets and liabilities and for operating losses and tax credit carry forwards, using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is recorded if it is "more likely than not" that a portion or all of a deferred tax asset will not be realized.
Other Comprehensive Income/ (Loss)	Other Comprehensive Income/ (Loss) Components of other comprehensive income/(loss) include unrealized gains and losses on available-for-sale securities and are included in the statements of comprehensive loss.
Leases	Leases In the ordinary course of business, the Company enters into lease agreements for office space as well as leases for certain property and equipment. The leases have varying terms and expirations and have provisions to extend or renew the lease agreement, among other terms and conditions, as negotiated. Once the agreement is executed, the lease is assessed to determine whether the lease qualifies as a capital or operating lease. When a non-cancelable operating lease includes any fixed escalation clauses and lease incentives for rent holidays or build-out contributions, rent expense is recognized on a straight-line basis over the initial term of the lease. The excess between the average rental amount charged to expense and amounts payable under the lease is recorded in accrued expenses.
Nonqualified Cash Deferral Plan	Nonqualified Cash Deferral Plan In July 2014, the Board of Directors approved the Company's Cash Deferral Plan (the "Deferral Plan"), which provides certain key employees and members of the Board of Directors as selected by the Compensation Committee of the Board of Directors of the Company (the "Compensation Committee"), with an opportunity to defer the receipt of such Participant's base salary, bonus and director's fees, as applicable. The Deferral Plan is intended to be a nonqualified deferred compensation plan that complies with the provisions of Section 409A of the Internal Revenue Code (the "Code"). All of the investments held in the Deferral Plan will be classified as investments held-to-maturity and recorded at fair value with changes in the investments' fair value recognized as earnings in the period they occur. The corresponding liability for the Deferral Plan is included in other non-current liability in our consolidated balance sheets.
Equity Incentive Plan	Equity Incentive Plan In June 2014, our stockholders approved the Amended and Restated 2007 Equity Incentive Plan (the "Plan"). The amendment to the Plan makes an additional 6.0 million shares of our common stock available for issuance and increases the maximum number of shares within the Plan that may be issued as restricted stock, restricted stock units ("RSUs"), stock grants and any other similar awards from 1.1 million to 1.5 million shares. As of December 31, 2015, awards issued under the Plan include both stock options and RSUs.
Stock-Based Compensation	Stock-Based Compensation At December 31, 2015, the Company had three stock-based employee compensation plans, which are described more fully in "— Note 9. Stockholders' Equity." The Company applies the fair value method of measuring stock-based compensation, which requires a public entity to measure the cost of employee services received in exchange for an award of equity instruments based on the grant-date fair value of the award.
Loss per Common Share	Loss 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 had a net loss for all periods presented; accordingly, the inclusion of common stock options, unvested restricted stock units ("RSUs") and warrants would be anti-dilutive. Therefore, the weighted average shares used to calculate both basic and diluted earnings per share are the same. See "— Note 18. Earnings per Share" for further discussion on net loss per share.
Dividends	Dividends The Company has not paid cash dividends on its capital stock to date. The Company currently intends to retain its future earnings, if any, to fund the development and growth of the business and does not foresee payment of a dividend in any upcoming fiscal period.
Segment Information	Segment Information The Company currently operates in one business segment focused on the discovery, development and commercialization of advanced therapies to treat a range of devastating rare and orphan diseases. The Company is not organized by market and is managed and operated as one business. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate service lines and does not have separately reportable segments.
Business Combinations	Business Combinations The Company allocates the purchase price of acquired businesses to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets and in-process research and development ("IPR&D"). In connection with the purchase price allocations for acquisitions, the Company estimates the fair value of contingent payments utilizing a probability-based income approach inclusive of an estimated discount rate.
Contingent Consideration Payable	Contingent Consideration Payable The Company determines the fair value of contingent acquisition consideration payable on the acquisition date using a probability-based income approach utilizing an appropriate discount rate. Contingent acquisition consideration payable is shown as a non-current liability on the Company's consolidated balance sheets. Changes in the fair value of the contingent acquisition consideration payable will be determined each period end and recorded on the consolidated statements of operations.
Intangible Assets and Goodwill	Intangible Assets and Goodwill The Company records goodwill in a business combination when the total consideration exceeds the fair value of the net tangible and identifiable intangible assets acquired. Purchased IPR&D is accounted for as an indefinite lived intangible asset until the underlying project is completed, at which point the intangible asset will be accounted for as a definite lived intangible asset, or abandoned, at which point the intangible asset will be written off or partially impaired. Goodwill and indefinite lived intangible assets are assessed annually for impairment and whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. If it is determined that the full carrying amount of an asset is not recoverable, an impairment loss is recorded in the amount by which the carrying amount of the asset exceeds its fair value.
Restructuring	Restructuring Restructuring charges are recognized as a result of actions to streamline operations and rationalize manufacturing facilities. Judgment is used when estimating the impact of restructuring plans, including future termination benefits and other exit costs to be incurred when the actions take place. Actual results could vary from these estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2015, the FASB issued the Accounting Standards Update ("ASU") No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. The amendments in ASU 2015-17 eliminates the current requirement for organizations to present deferred tax liabilities and assets as current and noncurrent in a classified balance sheet. Instead, organizations will be required to classify all deferred tax assets and liabilities as noncurrent. The ASU is effective for financial statements beginning after December 15, 2016, and interim periods within those annual periods. The amendments may be applied prospectively to all deferred tax liabilities and assets or retrospectively to all periods presented. The Company has early adopted this standard as of December 31, 2015 on a retrospective basis and this standard had no impact on its consolidated financial statements. In September 2015, the FASB issued ASU 2015-16 Business Combinations (Topic 805 ): Simplifying the Accounting for Measurement-Period Adjustments . The amendments in ASU 2015-16 require that an acquirer recognize adjustments to estimated amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments require that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the estimated amounts, calculated as if the accounting had been completed at the acquisition date. The amendments also require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the estimated amounts had been recognized as of the acquisition date. The ASU is effective for public business entities for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. Early adoption is permitted for financial statements that have not been issued. The Company has early adopted this standard as of September 30, 2015 and this standard had no impact on its consolidated financial statements. In April 2015, the FASB issued ASU 2015-05, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The amendments in ASU 2015-05 provide guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The amendments do not change the accounting for a customer's accounting for service contracts. As a result of the amendments, all software licenses within the scope of Subtopic 350-40 will be accounted for consistent with other licenses of intangible assets. The ASU is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. In April 2015, the FASB issued ASU 2015-03, Interest — Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . The amendments in ASU 2015-03 are intended to simplify the presentation of debt issuance costs. These amendments require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this ASU. The ASU is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted and the Company has adopted this ASU as of December 31, 2015. The guidance in ASU 2015-03 (see paragraph 835-30-45-1A) does not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. Given the absence of authoritative guidance within ASU 2015-03 for debt issuance costs related to line-of-credit arrangements, the SEC staff stated in June 2015 that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. ASU 2015-15 Imputation of Interest adds the SEC paragraph to the Topic. The Company early adopted this ASU as of December 31, 2015 and the adoption does not have an impact on its consolidated financial statements. In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern, which defines management's responsibility to assess an entity's ability to continue as a going concern, and to provide related footnote disclosures if there is substantial doubt about its ability to continue as a going concern. The pronouncement is effective for annual reporting periods ending after December 15, 2016 with early adoption permitted. The adoption of this guidance is not expected to have a significant impact on our consolidated financial statements. In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers that outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The ASU is based on the principle that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to fulfill a contract. Entities have the option of using either a full retrospective or a modified retrospective approach for the adoption of the new standard. In July 2015, the Financial Accounting Standards Board voted to delay the effective date of this standard until the first quarter of 2018. Companies are permitted to early adopt the standard in the first quarter of 2017. Presently, the Company is assessing the effect the adoption of ASU 2014-09 will have on its consolidated financial statements.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2015
Acquisitions
Schedule of allocation of purchase consideration, including the contingent acquisition consideration payable, based on fair value	The final valuation was completed as of December 31, 2015. (in thousands) Upfront cash payments $ Upfront equity payments Contingent acquisition consideration payable ​ ​ ​ ​ ​ Total consideration Property, plant and equipment, net Intangible assets — In-process Research and Development ("IPR&D") ​ ​ ​ ​ ​ Total identifiable assets acquired Deferred tax liability ) ​ ​ ​ ​ ​ Total liabilities assumed ) Net identifiable assets acquired Goodwill ​ ​ ​ ​ ​ Net assets acquired $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of unaudited consolidated pro forma financial information	Year ended December 31, Unaudited Pro Forma Consolidated Information: 2015 2014 (in thousands) Revenue $ — $ Net loss Scioderm $ ) $ ) Net loss combined $ ) $ )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets
Schedule of changes in goodwill	(in millions) Balance at December 31, 2014 $ Goodwill related to Scioderm on date of acquisition (See Note 3) ​ ​ ​ ​ ​ Balance at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule representing the changes in IPR&D	(in millions) Balance at December 31, 2014 $ IPR&D related to Scioderm on date of acquisition (See Note 3) ​ ​ ​ ​ ​ Balance at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Cash, Money Market Funds and 32

Cash, Money Market Funds and Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and December 31, 2014 (in thousands): As of December 31, 2015 Cost Unrealized Gain Unrealized Loss Fair Value Cash balances $ $ — $ — $ Corporate debt securities, current portion ) Commercial paper — Certificate of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Included in cash and cash equivalents $ $ — $ — $ Included in marketable securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and marketable securities $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2014 Cost Unrealized Gain Unrealized Loss Fair Value Cash balances $ $ — $ — $ Corporate debt securities, current portion — ) Corporate debt securities, non-current portion — ) Commercial paper — Certificate of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Included in cash and cash equivalents $ $ — $ — $ Included in marketable securities ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total cash and marketable securities $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
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 years ended December 31, 2015 and 2014, were as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance, beginning $ ) $ $ Current period changes in fair value, ) ) Reclassification of earnings, — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, ending $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property and Equipment
Schedule of property and equipment	Property and equipment consist of the following (in thousands): December 31, 2015 2014 Property and equipment consist of the following: Computer equipment $ $ Computer software Research equipment Furniture and fixtures Leasehold improvements ​ ​ ​ ​ ​ ​ ​ ​ Less accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Accounts Payable, Accrued Exp34

Accounts Payable, Accrued Expenses and Long-Term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Accounts Payable, Accrued Expenses and Long-Term Liabilities
Schedule of accounts payable and accrued expenses	Accounts payable and accrued expenses consist of the following (in thousands): December 31, 2015 2014 Accounts payable $ $ Accrued professional fees Accrued contract manufacturing & contract research costs Accrued compensation and benefits Accrued facility costs Contingent success fee payable — Accrued other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Other long-term liabilities	Other long-term liabilities consist of the following (in thousands): December 31, 2015 2014 Exit fees $ — $ Employee compensation and benefits Security deposits ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity
Schedule of fair value weighted-average assumptions	Years Ended December 31, 2015 2014 2013 Expected stock price volatility % % % Risk free interest rate % % % Expected life of options (years) Expected annual dividend per share $ $ $
Summary of stock options	Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life Aggregate Intrinsic Value (in thousands) (in millions) Options outstanding, December 31, 2012 $ Granted $ Exercised — — Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2013 $ Granted $ Exercised ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2014 $ Granted $ Exercised ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding, December 31, 2015 $ 7.3 years $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested and unvested expected to vest, December 31, 2015 $ 7.2 years $ Exercisable at December 31, 2015 $ 5.7 years $
Summary of information on the Company's restricted stock units	Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Years Aggregate Intrinsic Value (in thousands) (in millions) Non-vested units as of December 31, 2014 $ Granted $ Vested ) $ — Forfeited — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested units as of December 31 ,2015 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of the stock-based compensation expense recognized in the statements of operations	The following table summarizes the stock-based compensation expense recognized in the statements of operations (in thousands): Years Ended December 31, 2015 2014 2013 Stock compensation expense recognized in: Research and development expense $ $ $ General and administrative expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total stock compensation expense $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Assets and Liabilities Measur36

Assets and Liabilities Measured at Fair Value (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of changes in contingent consideration payable	Year ended December 31, 2015 2014 Balance, beginning of the period $ $ Additions, from business acquisitions — Unrealized change in fair value change during the period, included in Statement of Operations ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of the period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of assets and liabilities subject to fair value measurements	A summary of the fair value of the Company's recurring assets and liabilities aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2015 are identified in the following table (in thousands): Level 1 Level 2 Total Assets: Cash/money market funds $ $ — $ Commercial paper — Corporate debt securities — Certificate of deposit — Deferred compensation plan assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2 Level 3 Total Liabilities: Contingent consideration payable $ — $ $ Deferred compensation plan liability — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following is a summary of the Company's non-recurring liability aggregated by the level in the fair value hierarchy within which those measurements fall as of December 31, 2015 are identified in the following table (in thousands): Level 3 Liabilities: Note payable to related party $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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, 2014 are identified in the following table (in thousands): Level 1 Level 2 Total Assets: Cash/money market funds $ $ — $ Commercial paper — Corporate debt securities — Certificate of deposit — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2 Level 3 Total Liabilities: Contingent success fee payable — Contingent consideration payable — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ — $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Scioderm
Schedule of significant unobservable inputs used in the valuation of the contingent consideration payable	Contingent Consideration Liability Fair value as of December 31, 2015 Valuation Technique Unobservable Input Range Discount rate 0.7% - 1.5% Clinical and regulatory milestones $236.7 million Probability weighted discounted cash flow Probability of achievement of milestones 66.5% - 70% Projected year of payments 2016 - 2019 Revenue volatility 58% Revenue-based milestones $21.1 million Monte Carlo Discount rate 1.3% - 2.4% Projected year of payments 2018 - 2028
Callidus
Schedule of significant unobservable inputs used in the valuation of the contingent consideration payable	The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Callidus: Contingent Consideration Liability Fair value as of December 31, 2015 Valuation Technique Unobservable Input Range Discount rate 11.5% Clinical and regulatory milestones $16.3 million Probability weighted discounted cash flow Probability of achievement of milestones 30% - 95% Projected year of payments 2016 - 2026

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Leases
Schedule of Real Estate Properties	The following table contains information about our current significant leased properties as of December 31, 2015: Location Approximate Square Feet Use Lease expiry date Cranbury, New Jersey Office and laboratory September 2025 San Diego, California Office and laboratory September 2016 Durham, North Carolina Office and laboratory June 2016 Buckinghamshire, United Kingdom Office September 2020 Munich, Germany Office April 2017
Schedule of aggregate annual future minimum lease payments under the leases	At December 31, 2015, aggregate annual future minimum lease payments, net of income from subleases, under these leases are as follows: (in thousands) 2016 2017 2018 2019 2020 and beyond Total Minimum lease payments $ $ $ $ $ $ Less: income from sublease ) — — — — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net minimum lease payments $ $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Taxes
Schedule of significant components of the deferred tax assets and liabilities	The significant components of the deferred tax assets and liabilities are as follows (in thousands): For Years Ended December 31, 2015 2014 Non-current deferred tax assets Amortization/depreciation $ $ Research tax credit Net operating loss carry forwards Deferred revenue Non-cash stock issue $ $ Others ​ ​ ​ ​ ​ ​ ​ ​ Gross deferred tax assets Deferred tax liability related to business acquisition ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total net deferred tax asset Less valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets (liability) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of income (loss) before income taxes	For financial reporting purposes, income (loss) before income taxes includes the following components (in thousands): Years Ended December 31, 2015 2014 2013 United States $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of reconciliation of the statutory tax rates and the effective tax rates	Years Ended December 31, 2015 2014 2013 Statutory rate )% )% )% State taxes, net of federal benefit ) ) ) Permanent adjustments ) R&D credit ) ) ) Foreign income tax rate differential — — Other — Valuation allowance ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net )% )% )% ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Short-Term Borrowings and Lon39

Short-Term Borrowings and Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Short-Term Borrowings and Long-Term Debt
Schedule of remaining future minimum payments of principal due	The remaining future minimum payments of principal due as of December 31, 2015 are as follows (in thousands): Years ending December 31: 2016 $ — 2017 2018 — 2019 — 2020 and beyond ​ ​ ​ ​ ​ Total principal obligation Less short-term portion (— ) ​ ​ ​ ​ ​ Long-term portion Less debt discount ) ​ ​ ​ ​ ​ Long term portion, net of debt discount $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Restructuring Charges (Tables)

Restructuring Charges (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring Charges
Summary of restructuring charges and utilization	The following table summarizes the restructuring charges and utilization for the year ended December 31, 2015 (in thousands): Balance as of December 31, 2014 Charges Cash Payments Adjustments Balance as of December 31, 2015 Facilities consolidation — )

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings per Share
Schedule of reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share	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 (in thousands except share amounts): Years Ended December 31, 2015 2014 2013 Historical Numerator: Net loss attributable to common stockholders $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: Weighted average common shares outstanding — basic and diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of potential shares of common stock that were excluded from the computation as they were anti-dilutive using the treasury stock method	The table below presents potential shares of common stock that were excluded from the computation as they were anti-dilutive using the treasury stock method (in thousands): Year ended December 31, 2015 2014 2013 Options to purchase common stock Outstanding warrants, convertible to common stock Unvested restricted stock units — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total number of potentially issuable shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Selected Quarterly Financial 42

Selected Quarterly Financial Data (Unaudited - in thousands except per share data) (Tables)	12 Months Ended
	Dec. 31, 2015
Selected Quarterly Financial Data (Unaudited - in thousands except per share data)
Schedule of selected quarterly financial data	Selected Quarterly Financial Data (Unaudited — in thousands except per share data) Quarters Ended March 31 June 30 September 30 December 31 2015 Net loss $ ) $ ) $ ) $ ) Basic and diluted net loss per common share (1) ) ) ) ) 2014 Net loss $ ) $ ) $ ) $ ) Basic and diluted net loss per common share (1) ) ) ) ) (1) Per common share amounts for the quarters and full years have been calculated separately. Accordingly, quarterly amounts do not add to the annual amounts because of differences on the weighted-average common shares outstanding during each period principally due to the effect of the Company issuing shares of its common stock during the year.

Description of Business (Detail

Description of Business (Details) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Oct. 31, 2015USD ($)shares	Jun. 30, 2015USD ($)$ / sharesshares	Nov. 30, 2014USD ($)$ / sharesshares	Jul. 31, 2014USD ($)$ / sharesshares	Nov. 30, 2013USD ($)item	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)	Feb. 19, 2016USD ($)
Corporate Information, Status of Operations and Management Plans
Net proceeds from stock issued at ATM transactions							$ 38,636
Accumulated deficit						$ 579,566	447,448
Shares Issued, Price Per Share | $ / shares		$ 13.25	$ 6.50
Stock issued from public offering / financing (in shares) | shares		19,500,000	15,900,000
Proceeds from the issuance of common stock (in dollars)		$ 243,000	$ 97,200			$ 243,042	$ 135,805	$ 15,000
Common Stock, Par or Stated Value Per Share | $ / shares			$ 0.01			$ 0.01	$ 0.01
GSK | Revised Agreement
Corporate Information, Status of Operations and Management Plans
Number of major markets outside the U.S. from whom parties to contractual arrangement is eligible to receive single-digit royalties on net sales | item					8
Number of major markets outside the U.S. from whom parties to contractual arrangement is eligible to receive post-approval and sales-based milestones | item					8
Other consideration paid					$ 0
Cowen and Company, LLC
Corporate Information, Status of Operations and Management Plans
Net proceeds from stock issued at ATM transactions				$ 38,600
Number of shares issued from ATM transactions (in shares) | shares				14,300,000
Aggregate offering proceeds				$ 40,000
Stock issued from public offering / financing (in shares) | shares				14,300,000
Proceeds from the issuance of common stock (in dollars)				$ 38,600
Common Stock, Par or Stated Value Per Share | $ / shares				$ 0.01
Common Stock
Corporate Information, Status of Operations and Management Plans
Net proceeds from stock issued at ATM transactions							$ 143
Number of shares issued from ATM transactions (in shares) | shares							14,328,224
Stock issued from public offering / financing (in shares) | shares						19,528,302	15,927,500
Additional Paid-In Capital
Corporate Information, Status of Operations and Management Plans
Net proceeds from stock issued at ATM transactions							$ 38,493
October 2015 Purchase Agreement | Redmile Group
Corporate Information, Status of Operations and Management Plans
Warrant term	5 years
Shares issuable for warrants (in shares) | shares	1,300,000
Unsecured notes	$ 50,000
Maximum | February 2016 Purchase Agreement | Redmile Group
Corporate Information, Status of Operations and Management Plans
Unsecured notes									$ 75,000

Summary of Significant Accoun44

Summary of Significant Accounting Policies - PP&E (Details)	12 Months Ended
	Dec. 31, 2015
Minimum
Property and Equipment
Estimated useful lives	3 years
Maximum
Property and Equipment
Estimated useful lives	5 years

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Equity Incentive (Details) shares in Millions	May. 31, 2014shares	Jun. 30, 2014shares	Dec. 31, 2015item
Stock-Based Compensation
Number of stock-based employee compensation plans | item			3
2007 Plan and 2007 Director Plan
Equity Incentive Plan
Additional shares available for issuance		6
2007 Plan and 2007 Director Plan | Minimum
Equity Incentive Plan
Maximum number of restricted stock, RSUs, stock grants or similar awards that may be issued	1.1
2007 Plan and 2007 Director Plan | Maximum
Equity Incentive Plan
Maximum number of restricted stock, RSUs, stock grants or similar awards that may be issued	1.1	1.5

Summary of Significant Accoun46

Summary of Significant Accounting Policies - Segment (Details)	12 Months Ended
	Dec. 31, 2015item
Segment Information
Number of business segments	1

Acquisitions (Details)

Acquisitions (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2015	Nov. 30, 2013	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2014	Dec. 31, 2013
Acquisitions
Common stock, par value (in dollars per share)	$ 0.01				$ 0.01	$ 0.01	$ 0.01	$ 0.01
Current portion of contingent consideration payable	$ 41,400				$ 41,400	$ 41,400
Changes in fair value of contingent consideration payable						4,377	$ 100
Allocation of the purchase consideration, including the contingent acquisition consideration payable
Contingent acquisition consideration payable	274,077			$ 10,600	274,077	274,077	10,700		$ 10,600
Intangible assets-IPR&D	486,700				486,700	486,700	23,000
Goodwill.	197,797				197,797	197,797	11,613
Scioderm
Acquisitions
Initial amount to Effective Time Holders		$ 223,900
Common stock issued on acquisition (in shares)		5.9
Fair value of the contingent consideration payments	257,800	$ 259,000
Additional payment to be made upon achievement of regulatory approval			$ 361,000
Additional payment to be made upon achievement of sales milestones			257,000
Priority Review Voucher sale proceeds shared		$ 100,000
Priority review voucher transfer years		1 year
Current portion of contingent consideration payable	35,800				35,800	35,800
Changes in fair value of contingent consideration payable	1,200
Allocation of the purchase consideration, including the contingent acquisition consideration payable
Upfront cash payments		$ 141,100	141,100			141,060
Upfront equity payments		82,800	82,800			82,846
Contingent acquisition consideration payable	259,000				259,000	259,000
Property, plant and equipment, net	55				55	55
Intangible assets-IPR&D	463,700				463,700	463,700
Total identifiable assets acquired	463,755				463,755	463,755
Deferred tax liability	(167,033)				(167,033)	(167,033)
Total liabilities assumed	(167,033)				(167,033)	(167,033)
Net identifiable assets acquired	296,722				296,722	296,722
Goodwill.	186,184				186,184	186,184
Net assets acquired	482,906				482,906	482,906
Supplemental Pro Forma Information
Revenue					0		1,224
Net loss						(10,078)	(6,461)
Net loss combined						(142,196)	$ (75,387)
Scioderm | Zorblisa
Allocation of the purchase consideration, including the contingent acquisition consideration payable
Intangible assets-IPR&D	463,700				463,700	463,700
Scioderm | Maximum
Acquisitions
Additional payment to be made upon achievement of sales milestones		257,000
Priority Review Voucher sale proceeds shared		$ 100,000
Priority Review Voucher sale proceeds shared (as a percent)		50.00%
Allocation of the purchase consideration, including the contingent acquisition consideration payable
Contingent acquisition consideration payable		$ 361,000	$ 361,000
Callidus
Acquisitions
Common stock issued on acquisition (in shares)				7.2
Common stock, par value (in dollars per share)				$ 0.01
Maximum merger consideration to be transferred				$ 130,000
Milestone payment that can be settled in equity				$ 40,000
Number of trading days immediately preceding the date of payment on basis of which issue price will be determined				10 days
Current portion of contingent consideration payable	5,600				5,600	5,600
Changes in fair value of contingent consideration payable						5,600
Allocation of the purchase consideration, including the contingent acquisition consideration payable
Contingent acquisition consideration payable	$ 16,300				$ 16,300	16,300
Acquisition-related transaction costs						$ 3,100
Callidus | Maximum
Acquisitions
Additional payment to be made upon achievement of clinical milestone				$ 35,000
Additional payment to be made upon achievement of regulatory approval				$ 105,000
Clinical and Regulatory milestones | Scioderm | Minimum
Acquisitions
Discount rate (as a percent)		0.70%
Clinical and Regulatory milestones | Scioderm | Maximum
Acquisitions
Discount rate (as a percent)		1.50%
Revenue-based milestones | Scioderm | Minimum
Acquisitions
Discount rate (as a percent)		1.30%
Revenue-based milestones | Scioderm | Maximum
Acquisitions
Discount rate (as a percent)		2.40%

Goodwill and Intangible Asset48

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2015
Changes in goodwill
Balance at beginning of the period		$ 11,613
Balance at end of the period		197,797
Goodwill, Impairment Loss		0
Scioderm
Changes in goodwill
Goodwill related to the acquisition of Scioderm (See Note 4)	$ 186,200
Balance at end of the period		$ 186,184

Goodwill and Intangible Asset49

Goodwill and Intangible Assets - IPR&D (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Changes in IPR&D
Beginning balance intangible assets-IPR&D	$ 23,000
Ending balance intangible assets-IPR&D	486,700
Impairment of IPR&D	0
Scioderm
Changes in IPR&D
IPR&D related to the acquisition of Scioderm (See Note 4)	463,700
Ending balance intangible assets-IPR&D	$ 463,700

Cash, Money Market Funds and 50

Cash, Money Market Funds and Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash, Money Market Funds, and Marketable Securities
Cash and cash equivalents, Amortized Cost	$ 69,485	$ 24,074	$ 43,640	$ 33,971
Marketable securities, Amortized Cost	144,663	145,197
Unrealized Gain	39	22
Unrealized Loss	(154)	(154)
Cash and cash equivalents, Fair Value	69,485	24,074
Marketable securities, Fair Value	144,548	145,065
Marketable securities, Fair Value current portion	144,548	127,601
Marketable securities, Fair Value non-current portion		17,464
Cash and marketable securities, Amortized Cost	214,148	169,271
Cash and marketable securities, Fair Value	214,033	169,139
Available-for-sale investments
Realized gain (loss) on securities available-for-sale	0	0
Fair value of available for sale securities in unrealized loss positions	118,500	129,200
Changes in AOCI associated with the unrealized holding gain on available-for-sale investments
Balance, beginning	(132)	1	14
Current period changes in fair value	17	(133)	(13)
Balance, ending	(115)	(132)	$ 1
Short term corporate debt securities
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost	118,627
Marketable securities, Amortized cost current portion		115,862
Unrealized Gain	1
Unrealized Loss	(154)
Unrealized Loss current portion		(110)
Marketable securities, Fair Value	118,474
Marketable securities, Fair Value current portion		115,752
Long term corporate debt securities
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized cost non-current portion		17,508
Unrealized Loss Non-current portion		(44)
Marketable securities, Fair Value non-current portion		17,464
Commercial paper
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost	25,686	11,477
Unrealized Gain	38	22
Marketable securities, Fair Value	25,724	11,499
Certificate of deposit
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost	350	350
Marketable securities, Fair Value	$ 350	$ 350

Property and Equipment (Details

Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment
Property and equipment, gross	$ 19,531,000	$ 14,331,000
Less accumulated depreciation and amortization	(13,353,000)	(11,520,000)
Property and equipment, net	6,178,000	2,811,000
Depreciation and amortization	1,833,000	1,547,000	$ 1,719,000
Capital lease obligations outstanding	0
Computer equipment
Property and Equipment
Property and equipment, gross	5,075,000	3,555,000
Computer software
Property and Equipment
Property and equipment, gross	1,354,000	1,102,000
Research equipment
Property and Equipment
Property and equipment, gross	6,483,000	5,986,000
Furniture and fixtures
Property and Equipment
Property and equipment, gross	2,444,000	1,547,000
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 4,175,000	$ 2,141,000

Accounts Payable, Accrued Exp52

Accounts Payable, Accrued Expenses and Long-Term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued expenses
Accounts payable	$ 16,477	$ 5,874
Accrued professional fees	3,578	473
Accrued contract manufacturing & contract research costs	2,940	3,321
Accrued compensation and benefits	6,201	5,051
Accrued facility costs	1,321	557
Contingent success fee payable		341
Accrued other	1,699	728
Accounts payable and accrued expenses	32,216	16,345
Other long-term liabilities
Exit fees		450
Employee compensation and benefits	667	124
Security deposits	14	14
Total Other long-term liabilities	$ 681	$ 588

Related Party Transaction (Deta

Related Party Transaction (Details) - Redmile - USD ($) $ in Millions	Sep. 28, 2015	Feb. 19, 2016	Dec. 31, 2015
October 2015 Purchase Agreement
Related Party Transaction
Proceeds from Issuance of Debt	$ 50
Ownership position in the company (as a percent)			6.70%
February 2016 Purchase Agreement
Related Party Transaction
Unsecured notes		$ 75

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock and Warrants (Details) $ / shares in Units, $ in Thousands

Feb. 26, 2016USD ($)$ / shares

Sep. 30, 2015USD ($)shares

Oct. 31, 2015USD ($)shares

Sep. 30, 2015USD ($)shares

Jun. 30, 2015USD ($)$ / sharesshares

Nov. 30, 2014USD ($)$ / sharesshares

Jul. 31, 2014USD ($)$ / sharesshares

Nov. 30, 2013USD ($)$ / sharesshares

Dec. 31, 2015USD ($)item$ / sharesshares

Dec. 31, 2014USD ($)$ / sharesshares

Dec. 31, 2013USD ($)

Feb. 19, 2016USD ($)

Stockholders' Equity

Authorized number of shares of common stock | shares

250,000,000

125,000,000

Voting right for each share held, number | item

1

Collaborative Agreements

Stock issued from public offering / financing (in shares) | shares

19,500,000

15,900,000

Offering price (in dollars per share) | $ / shares

$ 13.25

$ 6.50

Net proceeds from the issuance of common stock

$ 243,000

$ 97,200

$ 243,042

$ 135,805

$ 15,000

Proceeds from Warrant Exercises

$ 4,000

Common stock, par value (in dollars per share) | $ / shares

$ 0.01

$ 0.01

$ 0.01

Net proceeds from stock issued at ATM transactions

$ 38,636

Remaining term of the warrants

5 years

Cowen and Company, LLC

Collaborative Agreements

Stock issued from public offering / financing (in shares) | shares

14,300,000

Net proceeds from the issuance of common stock

$ 38,600

Common stock, par value (in dollars per share) | $ / shares

$ 0.01

Aggregate offering proceeds from issuance of common stock

$ 40,000

Net proceeds from stock issued at ATM transactions

$ 38,600

Number of shares issued from ATM transactions (in shares) | shares

14,300,000

Cowen and Company, LLC | Sales Agreement

Collaborative Agreements

Common stock, par value (in dollars per share) | $ / shares

$ 0.01

Cowen and Company, LLC | Sales Agreement | Maximum

Collaborative Agreements

Aggregate offering price

$ 100,000

Redmile Group

Collaborative Agreements

Offering price (in dollars per share) | $ / shares

$ 13.75

Volatility (as a percent)

75.10%

Riskless rate of return (as a percent)

1.37%

Redmile Group | Private Placement Purchase Agreement

Collaborative Agreements

Proceeds received from private placement

$ 50,000

Redmile Group | Private Placement Purchase Agreement | Warrants

Collaborative Agreements

Shares issuable for warrants (in shares) | shares

1,300,000

Fair value of the warrant liability

$ 8,800

Remaining term of the warrants

5 years

Volatility (as a percent)

75.10%

Annual rate of dividends (as a percent)

0.00%

Riskless rate of return (as a percent)

1.37%

Value of the warrants

$ 10,600

Callidus

Collaborative Agreements

Common stock, par value (in dollars per share) | $ / shares

$ 0.01

Common stock issued on acquisition (in shares) | shares

7,200,000

Callidus | Maximum

Collaborative Agreements

Additional payment to be made upon achievement of regulatory approval

$ 105,000

Scioderm

Collaborative Agreements

Stock issued from public offering / financing (in shares) | shares

5,900,000

Consideration paid

$ 223,900

$ 482,906

Upfront cash payments

$ 141,100

141,100

141,060

Upfront equity payments

$ 82,800

82,800

$ 82,846

Additional payment to be made upon achievement of regulatory approval

361,000

Additional payment to be made upon achievement of sales milestones

$ 257,000

Common stock issued on acquisition (in shares) | shares

5,900,000

Scioderm | Maximum

Collaborative Agreements

Additional payment to be made upon achievement of sales milestones

$ 257,000

October 2015 Purchase Agreement | Redmile Group

Collaborative Agreements

Shares issuable for warrants (in shares) | shares

1,300,000

Unsecured notes

$ 50,000

Warrant term

5 years

February 2016 Purchase Agreement | Redmile Group | Maximum

Collaborative Agreements

Unsecured notes

$ 75,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity
Deferred compensation liability, noncurrent	$ 700,000	$ 100,000
Income from deferred compensation investments	17,000
Trading securities	700,000
Unrealized gain/loss	50,000
Equity compensation expense	$ 9,972,000	6,008,000	$ 6,177,000
Minimum stock price volatility (as a percent)	75.00%
Common stock options
Stockholders' Equity
Total unrecognized compensation cost related to non-vested stock options granted (in dollars)	$ 24,600,000
Period of recognition compensation cost	3 years 1 month 6 days
Aggregate intrinsic value of options exercised (in dollars)	$ 14,700,000	2,800,000
Cash proceeds from stock options exercised (in dollars)	$ 11,200,000	$ 3,700,000
Weighted-average grant-date fair value per share of options granted (in dollars per share)	$ 7.51	$ 2.12	$ 2.14
Fair value weighted-average assumptions:
Expected stock price volatility (as a percent)	75.90%	81.30%	82.00%
Risk free interest rate (as a percent)	1.70%	1.90%	1.30%
Expected life of options	6 years 3 months	6 years 3 months	6 years 3 months
Expected annual dividend per share (in dollars per share)	$ 0	$ 0	$ 0
Number of Shares
Balance at the beginning of the period (in shares)	10,020,700	9,041,100	7,974,200
Options granted (in shares)	3,917,200	2,993,100	2,481,800
Options exercised (in shares)	(2,070,300)	(965,600)
Options forfeited (in shares)	(138,400)	(1,047,900)	(1,414,900)
Balance at the end of the period (in shares)	11,729,200	10,020,700	9,041,100
Vested and unvested expected to vest at the end of the period (in shares)	10,912,100
Exercisable at the end of the period (in shares)	5,582,200
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 5.02	$ 5.65	$ 6.35
Options granted (in dollars per share)	11.61	2.99	3.04
Options exercised (in dollars per share)	5.43	3.80
Options forfeited (in dollars per share)	7.76	5.76	5.01
Balance at the end of the period (in dollars per share)	7.11	$ 5.02	$ 5.65
Vested and unvested expected to vest at the end of the period (in dollars per share)	6.95
Exercisable at the end of the period (in dollars per share)	$ 5.66
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	5 years 8 months 12 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)	$ 40,700
Aggregate intrinsic value of options vested and unvested expected to vest (in dollars)	39,000
Aggregate intrinsic value of options exercisable (in dollars)	$ 24,200
Restricted stock units (RSUs)
Stockholders' Equity
Restricted stock awards (in shares)	479,000
Number of Shares
Balance at the beginning of the period (in shares)	955,000
Balance at the end of the period (in shares)		955,000
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 2.28
Balance at the end of the period (in dollars per share)		$ 2.28
Aggregate Intrinsic Value
Aggregate intrinsic value, nonvested (in dollars)	$ 700,000
Restricted stock
Stockholders' Equity
Total unrecognized compensation cost related to non-vested stock options granted (in dollars)	$ 4,000,000
Period of recognition compensation cost	6 months

Stockholders' Equity - RSU Acti

Stockholders' Equity - RSU Activity (Details) - Restricted stock units (RSUs) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Number of Shares
Granted (in shares)	366
Vested (in shares)	(842)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	479
Weighted Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 12.63
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 10.38
Weighted Average Remaining Years
Weighted Average Remaining Years	1 year 11 months 23 days
Aggregate Intrinsic Value
Aggregate intrinsic value, nonvested (in dollars) | $	$ 0.7

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Plans (Details) - shares	May. 31, 2014	Jun. 30, 2014	Dec. 31, 2015
Common stock options
Stockholders' Equity
Maximum term of option			10 years
2002 Plan and 2007 Plan | Common stock options
Stockholders' Equity
Vesting rights percentage on the 13th month anniversary			25.00%
Additional percentage of options that will vest each month after first anniversary			2.08%
Percentage of shares vested that may be exercised in whole or part			100.00%
2007 Plan and 2007 Director Plan
Stockholders' Equity
Additional shares available for issuance		6,000,000
2007 Plan and 2007 Director Plan | Maximum
Stockholders' Equity
Maximum number of restricted stock, RSUs, stock grants or similar awards that may be issued	1,100,000	1,500,000
2007 Plan and 2007 Director Plan | Maximum | Common stock options
Stockholders' Equity
Number of shares reserved for issuance			2,551,120

Stockholders' Equity - Compensa

Stockholders' Equity - Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity compensation expense
Total equity compensation expense	$ 9,972	$ 6,008	$ 6,177
Research and development expense
Equity compensation expense
Total equity compensation expense	4,600	2,703	3,583
General and administrative expense
Equity compensation expense
Total equity compensation expense	$ 5,372	$ 3,305	$ 2,594

Assets and Liabilities Measur59

Assets and Liabilities Measured at Fair Value (Details) $ / shares in Units, $ in Thousands	Sep. 30, 2015USD ($)	Oct. 31, 2015USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)$ / shares	Jun. 30, 2015$ / shares	Dec. 31, 2014USD ($)	Nov. 30, 2014$ / shares	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)
Financial assets and liabilities subject to fair value measurements
Transfer of assets from Level 1 to Level 2								$ 0
Transfer of assets from Level 2 to Level 1								0
Change in fair value of warrant liability							$ (908)
Warrant liability								8,755
Interest income					$ 929	$ 223	174
Contingent consideration payable
Balance at the beginning of the period			$ 10,600		10,700	10,600
Additions, from business acquisitions								259,000
Unrealized change in fair value change during the period, included in Statement of Operations					4,377	100
Balance at the end of the period			10,600	$ 274,077	274,077	10,700	10,600
Assets:
Cash/money market funds								69,485		$ 24,074		$ 43,640	$ 33,971
Trading Securities								700
Liabilities:
Contingent consideration payable, less current portion			10,600	274,077	$ 10,700	10,600	$ 10,600	274,077		10,700		$ 10,600
Note payable to related party								41,601
Weighted average assumptions used in the Black-Scholes valuation model for the warrants
Share Price | $ / shares									$ 13.25		$ 6.50
Remaining term of the warrants					5 years
Total
Contingent consideration payable
Balance at the beginning of the period					$ 10,700
Balance at the end of the period				274,077	274,077	10,700
Assets:
Cash/money market funds								69,485		24,074
Fair value of assets								214,691		169,139
Deferred compensation plan assets								658
Liabilities:
Contingent success fee payable										341
Contingent consideration payable, less current portion				274,077	10,700	10,700		274,077		10,700
Deferred compensation plan liability								667
Fair value of liabilities								274,744		11,041
Callidus
Contingent consideration payable
Balance at the end of the period				16,300	16,300
Liabilities:
Contingent consideration payable, less current portion				16,300	16,300			16,300
Callidus | Clinical and Regulatory milestones
Financial assets and liabilities subject to fair value measurements
Fair value of contingent payment					16,300
Scioderm
Contingent consideration payable
Balance at the end of the period				259,000	259,000
Liabilities:
Contingent consideration payable, less current portion				259,000	259,000			259,000
Scioderm | Clinical and Regulatory milestones
Financial assets and liabilities subject to fair value measurements
Fair value of contingent payment					236,700
Scioderm | Revenue-based milestones
Financial assets and liabilities subject to fair value measurements
Fair value of contingent payment					21,100
Minimum | Scioderm | Clinical and Regulatory milestones
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)	0.70%
Minimum | Scioderm | Revenue-based milestones
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)	1.30%
Maximum | Scioderm
Contingent consideration payable
Balance at the beginning of the period		$ 361,000		361,000
Balance at the end of the period	$ 361,000
Liabilities:
Contingent consideration payable, less current portion	$ 361,000	361,000		361,000
Maximum | Scioderm | Clinical and Regulatory milestones
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)	1.50%
Maximum | Scioderm | Revenue-based milestones
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)	2.40%
Corporate debt securities | Total
Assets:
Fair value of assets								118,474		133,216
Commercial paper | Total
Assets:
Fair value of assets								25,724		11,499
Certificate of deposit | Total
Assets:
Fair value of assets								350		350
Level 1
Assets:
Cash/money market funds								69,485		24,074
Fair value of assets								69,485		24,074
Level 2
Assets:
Fair value of assets								145,206		145,065
Deferred compensation plan assets								658
Liabilities:
Deferred compensation plan liability								667
Fair value of liabilities								667
Level 2 | Corporate debt securities
Assets:
Fair value of assets								118,474		133,216
Level 2 | Commercial paper
Assets:
Fair value of assets								25,724		11,499
Level 2 | Certificate of deposit
Assets:
Fair value of assets								350		350
Level 3
Contingent consideration payable
Balance at the beginning of the period					10,700
Balance at the end of the period				274,077	274,077	10,700
Liabilities:
Contingent success fee payable										341
Contingent consideration payable, less current portion				274,077	$ 10,700	$ 10,700		274,077		10,700
Fair value of liabilities								274,077		$ 11,041
Note payable to related party								$ 41,601
Level 3 | Callidus | Clinical and Regulatory milestones | Probability weighted discounted cash flow
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					11.50%
Level 3 | Scioderm | Revenue-based milestones | Monte Carlo
Financial assets and liabilities subject to fair value measurements
Revenue Volatality (as a percent)					58.00%
Level 3 | Minimum | Callidus | Clinical and Regulatory milestones | Probability weighted discounted cash flow
Financial assets and liabilities subject to fair value measurements
Probability of achievement of milestones (as a percent)					30.00%
Level 3 | Minimum | Scioderm | Clinical and Regulatory milestones | Probability weighted discounted cash flow
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					0.70%
Probability of achievement of milestones (as a percent)					66.50%
Level 3 | Minimum | Scioderm | Revenue-based milestones | Monte Carlo
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					1.30%
Level 3 | Maximum | Callidus | Clinical and Regulatory milestones | Probability weighted discounted cash flow
Financial assets and liabilities subject to fair value measurements
Probability of achievement of milestones (as a percent)					95.00%
Level 3 | Maximum | Scioderm | Clinical and Regulatory milestones | Probability weighted discounted cash flow
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					1.50%
Probability of achievement of milestones (as a percent)					70.00%
Level 3 | Maximum | Scioderm | Revenue-based milestones | Monte Carlo
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					2.40%
2013 Loan Agreement
Financial assets and liabilities subject to fair value measurements
Amount borrowed			$ 15,000
Redmile Group
Financial assets and liabilities subject to fair value measurements
Discount rate (as a percent)					0.00%
Weighted average assumptions used in the Black-Scholes valuation model for the warrants
Number of inputs used in fair value classification | item					6
Share Price | $ / shares								$ 13.75
Exercise price of warrants (in dollars per share) | $ / shares								$ 16.84
Expected stock price volatility (as a percent)					75.10%
Risk free interest rate (as a percent)					1.37%
Redmile Group | October 2015 Purchase Agreement
Financial assets and liabilities subject to fair value measurements
Warrant liability		8,800
Amount borrowed		50,000
Amortization expense				$ 400
Unsecured notes		$ 50,000
Liabilities:
Secured debt								$ 41,600
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits
Financial assets and liabilities subject to fair value measurements
Interest income					$ 17
Unrealized gain (loss) on securities					$ (50)

401(k) Plan (Details)

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
401 (k) Plan
Maximum contribution by the company as a percentage of employee's salary and bonus paid during the year	5.00%
Total contribution to the plan (in dollars)	$ 0.9	$ 0.6	$ 0.7

Leases (Details)

Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)ft²	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Minimum lease payments
2,016	$ 2,646
2,017	2,471
2,018	2,381
2,019	2,389
2020 and beyond	12,734
Total	22,621
Less: income from sublease
2,016	(180)
Total	(180)
Net minimum lease payments
2,016	2,466
2,017	2,471
2,018	2,381
2,019	2,389
2020 and beyond	12,734
Total	22,441
Operating Leases, Rent Expense, Net	$ 2,600	$ 2,400	$ 2,600
Cranbury New Jersey [Member]
Operating Leases
Area of laboratory and office space leased (in square feet) | ft²	90,000
San Diego California
Operating Leases
Area of laboratory and office space leased (in square feet) | ft²	7,668
Durham North Carolina
Operating Leases
Area of laboratory and office space leased (in square feet) | ft²	3,180
Buckinghamshire United Kingdom
Operating Leases
Area of laboratory and office space leased (in square feet) | ft²	9,821
Munich Germany
Operating Leases
Area of laboratory and office space leased (in square feet) | ft²	4,316

Income Taxes - Deferred and Val

Income Taxes - Deferred and Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Recognized interest and penalties	$ 0
Accrual for interest and penalties	0
Accrual for uncertain tax positions	0
Non-current deferred tax assets
Amortization/depreciation	2,657	$ 2,910
Research tax credit	27,170	14,288
Net operating loss carry forwards	159,889	105,274
Deferred revenue	14,281	14,626
Non-cash stock issue	6,767	8,990
Others	2,964	2,347
Gross deferred tax assets	213,728	148,435
Deferred tax liability related to business acquisition	(176,219)	(9,186)
Total net deferred tax asset	37,509	139,249
Less valuation allowance	(213,728)	(148,435)
Net deferred tax assets (liability)	(176,219)	(9,186)
Increase in the valuation allowance	$ 68,600	$ 26,800

Income Taxes - Loss Carryforwar

Income Taxes - Loss Carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net operating loss carry forwards
Maximum change in ownership percentage allowed before statutory limitations imposed on the availability of net operating losses	50.00%
Period for measuring the change in ownership	3 years
Tax benefit associated with exercise of stock options to be recorded in additional paid-in capital on recognition of associated NOL	$ 3,600
Income (loss) before income taxes:
United States	(123,697)	$ (70,030)	$ (63,136)
Foreign	(8,421)	(9)	(9)
Loss before income tax benefit	(132,118)	$ (70,039)	$ (63,145)
Federal
Net operating loss carry forwards
Amount of net operating loss carry forwards	406,100
Foreign
Net operating loss carry forwards
Amount of net operating loss carry forwards	8,300
State
Net operating loss carry forwards
Amount of net operating loss carry forwards	$ 382,700

Income Taxes - Statutory Rate (

Income Taxes - Statutory Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of the statutory tax rates and the effective tax rates
Statutory rate (as a percent)	(34.00%)	(34.00%)	(34.00%)
State taxes, net of federal benefit (as a percent)	(5.00%)	(4.00%)	(5.00%)
Permanent adjustments (as a percent)	2.00%	1.00%	(1.00%)
R&D credit (as a percent)	(3.00%)	(4.00%)	(3.00%)
Foreign income tax rate differential	1.00%
Other (as a percent)		1.00%
Valuation allowance (as a percent)	39.00%	38.00%	37.00%
Net (as a percent)	0.00%	(2.00%)	(6.00%)
Income tax benefit from the sale of net operating losses and research and development credits		$ 1.1	$ 3.5

Licenses (Details)

Licenses (Details) - MSSM	12 Months Ended
	Dec. 31, 2015USD ($)
Licenses
Upfront and annual license fees paid	$ 0
Potential milestone payments	$ 0

Collaborative Agreements (Detai

Collaborative Agreements (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2013USD ($)item	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Collaborative Agreements
Research revenue for work performed under cost sharing arrangement		$ 1,224	$ 363
GSK | Revised Agreement
Collaborative Agreements
Upfront payment received	$ 0
Number of major markets outside the U.S. from whom parties to contractual arrangement is eligible to receive post-approval and sales-based milestones | item	8
Potential milestone payments upon achievement of post-approval and sales-based milestones	$ 40,000
Biogen Idec
Collaborative Agreements
Research revenue for work performed under cost sharing arrangement		$ 1,200

Short-Term Borrowings and Lon67

Short-Term Borrowings and Long-Term Debt (Details) $ in Thousands	1 Months Ended			3 Months Ended	12 Months Ended
	Oct. 31, 2015USD ($)installment	Jun. 30, 2015USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Feb. 19, 2016USD ($)	Dec. 31, 2014USD ($)
Short-Term Borrowings and Long-Term Debt
Long-term portion				$ 50,000	$ 50,000
Less debt discount				(8,399)	(8,399)
Extinguishment of Debt, Gain (Loss), Net of Tax					(952)
Remaining future minimum payments of principal due
2,017				15,000	15,000
2020 and beyond				35,000	35,000
Total principal obligation				50,000	50,000
Long-term portion				50,000	50,000
Less debt discount				(8,399)	(8,399)
Long term portion, net of debt discount				41,601	41,601
Level 3
Short-Term Borrowings and Long-Term Debt
Contingent success fee payable							$ 341
Remaining future minimum payments of principal due
Long term portion, net of debt discount				$ 41,601	$ 41,601
2013 Loan Agreement
Short-Term Borrowings and Long-Term Debt
Maximum amount of loan			$ 25,000
Fixed interest rate (as a percent)				8.50%	8.50%
Amount borrowed			$ 15,000
Contingent exit fee paid		$ 500
Contingent success fee paid		400
Extinguishment of Debt, Gain (Loss), Net of Tax		$ 1,000
Redmile Group | October 2015 Purchase Agreement
Short-Term Borrowings and Long-Term Debt
Fixed interest rate (as a percent)	4.10%
Amount borrowed	$ 50,000
Less debt discount	$ (8,800)
Warrant Term	5 years
Number of installments for repayment of debt | installment	2
Amortization expense				$ 400
Unsecured notes	$ 50,000
Remaining future minimum payments of principal due
Less debt discount	(8,800)
Redmile Group | February 2016 Purchase Agreement | Maximum
Short-Term Borrowings and Long-Term Debt
Unsecured notes						$ 75,000
Redmile Group | October 2017 payment | October 2015 Purchase Agreement
Short-Term Borrowings and Long-Term Debt
Installment payment	15,000
Redmile Group | October 2020 payment | October 2015 Purchase Agreement
Short-Term Borrowings and Long-Term Debt
Installment payment	$ 35,000

Restructuring Charges (Details)

Restructuring Charges (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2013item	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Restructuring charges
Restructuring charges		$ 2,000	$ 15	$ (63)	$ 1,988
Lease payments			2,600	2,400	2,600
Summary of restructuring charges and utilization
Charges		(2,000)	(15)	63	$ (1,988)
Employment termination costs
Restructuring charges
Restructuring charges		1,200
Summary of restructuring charges and utilization
Charges		(1,200)
Facilities consolidation
Restructuring charges
Number of subleased locations that were closed in consolidation | item	1
Restructuring charges		800
Lease payments		700
Write-down of the net book value of fixed assets		100
Summary of restructuring charges and utilization
Balance at the beginning of the period			283
Charges		$ (800)
Cash payments			(180)
Adjustments			15
Balance at the end of the period			$ 118	$ 283

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	13,558,000	12,576,000	12,045,000
Numerator:
Net loss attributable to common stockholders	$ (132,118)	$ (68,926)	$ (59,633)
Denominator:
Weighted average common shares outstanding - basic and diluted	109,923,815	74,444,157	51,286,059
Common stock options
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	11,729,000	10,021,000	9,041,000
Warrants
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	1,350,000	1,600,000	3,004,000
Restricted stock units (RSUs)
Antidilutive securities
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	479,000	955,000

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, shares in Millions, $ in Millions	Feb. 26, 2016USD ($)$ / shares	Feb. 19, 2016USD ($)installmentshares	Dec. 31, 2015$ / shares	Dec. 31, 2014$ / shares	Nov. 30, 2014$ / shares
Subsequent Events
Common stock, par value (in dollars per share) | $ / shares			$ 0.01	$ 0.01	$ 0.01
February 2016 Purchase Agreement | Redmile Group | Maximum
Subsequent Events
Unsecured notes		$ 75
Subsequent event | Sales Agreement | Cowen
Subsequent Events
Common stock, par value (in dollars per share) | $ / shares	$ 0.01
Subsequent event | Sales Agreement | Cowen | Maximum
Subsequent Events
Aggregate offering price	$ 100
Subsequent event | February 2016 Purchase Agreement | Redmile Group
Subsequent Events
Unsecured notes		75
Immediate available value of unsecured promissory notes		50
Conditional borrowing capacity		$ 25
Shares issuable for warrants (in shares) | shares		1.9
Warrant Term		5 years
Number of installments for repayment of debt | installment		2
Fixed interest rate (as a percent)		3.875%
October 2017 payment | Subsequent event | February 2016 Purchase Agreement | Redmile Group
Subsequent Events
Installment payment		$ 15
October 2021 payment | Subsequent event | February 2016 Purchase Agreement | Redmile Group
Subsequent Events
Installment payment		$ 35

Selected Quarterly Financial 71

Selected Quarterly Financial Data (Unaudited - in thousands except per share data) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Data
Net loss	$ (42,897)	$ (37,800)	$ (27,133)	$ (24,288)	$ (21,220)	$ (17,149)	$ (14,614)	$ (15,943)	$ (132,118)	$ (68,926)	$ (59,633)
Basic and diluted net loss per common share (in dollars per share)	$ (0.34)	$ (0.32)	$ (0.27)	$ (0.25)	$ (0.24)	$ (0.22)	$ (0.22)	$ (0.25)	$ (1.20)	$ (0.93)	$ (1.16)