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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2016	Feb. 15, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	AMICUS THERAPEUTICS INC
Entity Central Index Key	0001178879
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 542,291,868
Entity Common Stock, Shares Outstanding		194,824,362
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 187,026	$ 69,485
Investments in marketable securities	143,325	144,548
Accounts receivable	1,304
Inventories	3,416	0
Prepaid expenses and other current assets	4,993	2,568
Total current assets	340,064	216,601
Property and equipment, less accumulated depreciation of $12,495 and $13,353 at December 31, 2016 and 2015, respectively	9,816	6,178
In-process research & development	486,700	486,700
Goodwill	197,797	197,797
Other non-current assets	2,468	1,108
Total Assets	1,036,845	908,384
Current liabilities:
Accounts payable, accrued expenses , and other current liabilities	41,008	32,216
Deferred reimbursements, current portion	13,850
Contingent consideration payable, current portion	56,101	41,400
Total current liabilities	110,959	73,616
Deferred reimbursements	21,906	35,756
Convertible notes	154,464
Due to related party		41,601
Contingent consideration payable	213,621	232,677
Deferred income taxes	173,771	176,219
Other non-current liability	1,973	681
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value, 250,000,000 shares authorized, 142,691,986 shares issued and outstanding at December 31, 2016 Common stock, $.01 par value, 250,000,000 shares authorized, 125,027,034 shares issued and outstanding at December 31, 2015	1,480	1,306
Additional paid-in capital	1,120,156	917,454
Accumulated other comprehensive loss:
Foreign currency translation adjustment, less tax benefit of $1,293 at December 31, 2016	1,945
Unrealized gain/(loss) on available-for securities	102	(115)
Warrants	16,076	8,755
Accumulated deficit	(779,608)	(579,566)
Total stockholders' equity	360,151	347,834
Total Liabilities and Stockholders' Equity	$ 1,036,845	$ 908,384

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Consolidated Balance Sheets
Accumulated depreciation of property and equipment (in dollars)	$ 12,495	$ 13,353
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	142,691,986	125,027,034
Common stock, shares outstanding	142,691,986	125,027,034
Foreign currency translation adjustment, tax	$ 1,293

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Net Product Sales	$ 4,958
Research revenue			$ 1,224
Total revenue	4,958		1,224
Cost of goods sold	833
Gross Profit	4,125		1,224
Operating Expenses:
Research and development	104,793	$ 76,943	47,624
Selling, general and administrative	71,151	47,269	20,717
Changes in fair value of contingent consideration payable	6,760	4,377	100
Restructuring charges	69	15	(63)
Depreciation	3,242	1,833	1,547
Total operating expenses	186,015	130,437	69,925
Loss from operations	(181,890)	(130,437)	(68,701)
Other income (expenses):
Interest income	1,602	929	223
Interest expense	(5,398)	(1,578)	(1,484)
Loss on extinguishment of debt	(13,302)	(952)
Other expense	(4,793)	(80)	(77)
Loss before income tax benefit	(203,781)	(132,118)	(70,039)
Income tax benefit	3,739		1,113
Net loss attributable to common stockholders	$ (200,042)	$ (132,118)	$ (68,926)
Net loss attributable to common stockholders per common share - basic and diluted	$ (1.49)	$ (1.20)	$ (0.93)
Weighted-average common shares outstanding - basic and diluted	134,401,588	109,923,815	74,444,157

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Comprehensive Loss
Net loss	$ (200,042)	$ (132,118)	$ (68,926)
Other comprehensive gain/ (loss):
Foreign currency translation adjustment, net of tax of $1,293	1,945
Unrealized gain/ (loss) on available-for-sale securities	217	17	(133)
Other comprehensive income/ (loss)	2,162	17	(133)
Comprehensive loss	$ (197,880)	$ (132,101)	$ (69,059)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statements of Comprehensive Loss (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Consolidated Statements of Comprehensive Loss
Foreign currency translation adjustment, tax	$ (1,293)

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Scioderm Common Stock	Scioderm Additional Paid-In Capital	Scioderm	Callidus Common Stock	Callidus Additional Paid-In Capital	MiaMed Common Stock	MiaMed Additional Paid-In Capital	MiaMed	Common Stock	Additional Paid-In Capital	Warrants	Accumulated Other Comprehensive Gain/ (Loss)	Accumulated Deficit	Total
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 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 issued from public offering / financing									$ 159	97,010				97,169
Stock issued from public offering / financing (in shares)									15,927,500
Stock issued from ATM transactions									$ 143	38,493				38,636
Stock issued from ATM transactions (in shares)									14,328,224
Stock-based compensation										6,008				6,008
Unrealized holding gain/(loss) 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
Increase (Decrease) in Stockholders' Equity
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 for acquisition	$ 59	$ 82,787	$ 82,846
Stock issued for acquisition (in shares)	5,921,771			25,762
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 warrants									$ 16	3,984				4,000
Stock issued from exercise of warrants (in shares)									1,600,000
Restricted stock vesting										(2,044)				(2,044)
Restricted stock vesting (in shares)									324,622
Warrants issued in debt financing											$ 8,755			8,755
Stock-based compensation										9,972				9,972
Unrealized holding gain/(loss) 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
Increase (Decrease) in Stockholders' Equity
Stock issued from exercise of stock options, net									$ 7	3,029				$ 3,036
Stock issued from exercise of stock options, net (in shares)									723,102
Stock issued for acquisition						$ 8	$ 4,599	$ 4,607
Stock issued for acquisition (in shares)						825,603
Stock issued from ATM transactions									$ 150	96,918				97,068
Stock issued from ATM transactions (in shares)									14,989,027
Restricted stock vesting										(1,282)				(1,282)
Restricted stock vesting (in shares)									268,425
Stock issued for contingent consideration									$ 9	6,106				6,115
Stock issued for contingent consideration (in shares)									858,795
Receivable from investor										932				932
Warrants issued in debt financing											7,321			7,321
Equity component of the Convertible Notes issuance, net of issuance costs of $2,709										88,346				88,346
Premium paid for Capped Call Confirmations										(13,450)				(13,450)
Stock-based compensation										17,504				17,504
Unrealized holding gain/(loss) on available-for-sale securities												217		217
Foreign currency translation adjustment												1,945		1,945
Net loss													(200,042)	(200,042)
Balance at Dec. 31, 2016									$ 1,480	$ 1,120,156	$ 16,076	$ 2,047	$ (779,608)	$ 360,151
Balance (in shares) at Dec. 31, 2016									142,691,986					142,691,986

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) $ in Thousands	Dec. 31, 2016 USD ($)
Consolidated Statements of Changes in Stockholders' Equity
Convertible notes issuance costs	$ 2,709

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (200,042)	$ (132,118)	$ (68,926)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash interest expense	2,689	492	277
Depreciation	3,242	1,833	1,547
Stock-based compensation	17,504	9,972	6,008
Restructuring charges	69	15	(63)
Change in fair value of warrant liability	265
Non-cash changes in the fair value of contingent consideration payable	6,760	4,377	100
Charges to research expense for stock issued in asset acquisition	4,607
Loss on extinguishment of debt	13,302	952
Foreign currency remeasurement loss	3,660
Non-cash income tax benefit	(1,293)
Non-cash deferred taxes	(2,449)
Loss on disposal of assets	17
Changes in operating assets and liabilities:
Accounts receivable	(1,419)
Inventories	(3,651)
Receivable due from collaboration agreements			1,083
Prepaid expenses and other current assets	(394)	308	2,293
Other non-current assets	(1,357)	(666)	26
Accounts payable and accrued expenses	7,131	15,467	6,169
Non-current liabilities	825	93	(126)
Deferred reimbursements		(864)	(57)
Net cash used in operating activities	(150,534)	(100,139)	(51,669)
Investing activities
Sale and redemption of marketable securities	221,374	290,129	55,914
Purchases of marketable securities	(219,932)	(289,595)	(162,752)
Acquisitions, net of cash acquired		(141,060)
Purchases of property and equipment	(5,951)	(4,817)	(238)
Net cash used in investing activities	(4,509)	(145,343)	(107,076)
Financing activities
Proceeds from issuance of common stock and warrants, net of issuance costs	97,068	243,042	135,805
Payments of secured loan agreement	(80,000)	(15,291)	(299)
Payment of capital leases	(193)
Purchase of vested restricted stock units	(1,282)	(2,044)
Proceeds from exercise of stock options	3,036	11,186	3,673
Proceeds from exercise of warrants		4,000
Payment of contingent consideration	(5,000)
Proceeds from issuance of convertible senior notes, net of issuance costs	242,536
Premiums paid for Capped Call Confirmations	(13,450)
Proceeds from secured loan agreement	30,000	50,000
Net cash provided by financing activities	272,715	290,893	139,179
Effect of exchange rate changes on cash and cash equivalents	(131)
Net increase/(decrease) in cash and cash equivalents	117,541	45,411	(19,566)
Cash and cash equivalents at beginning of year/ period	69,485	24,074	43,640
Cash and cash equivalents at end of year/period	187,026	69,485	24,074
Supplemental disclosures of cash flow information
Cash paid during the period for interest	2,990	$ 605	$ 1,186
Contingent consideration paid in shares	6,115
Capital expenditures funded by capital lease borrowings	$ 944

Description of Business	12 Months Ended
Description of Business	Dec. 31, 2016
Description of Business
Description of Business	1. Description of Business Corporate Information, Status of Operations, and Management Plans Amicus Therapeutics, Inc. (the "Company") is a global patient-focused biotechnology company engaged in the discovery, development, and commercialization of a diverse set of novel treatments for patients living with devastating rare and orphan diseases. The lead product, migalastat HCl is a small molecule that can be used as a monotherapy and in combination with enzyme replacement of therapy ("ERT") for Fabry disease. The Company's Fabry franchise strategy is to develop migalastat HCl (which the Company may refer to as "migalastat") for all patients with Fabry disease as a monotherapy for patients with amenable mutations and in combination with ERT for all other patients. In May 2016, the Company announced that the European Commission ("EC") had granted full approval for the oral small molecule pharmacological chaperone Galafold™ (migalastat) as a first-line therapy for long-term treatment of adults and adolescents aged 16 years and older with a confirmed diagnosis of Fabry disease (alpha-galactosidase A deficiency) and who have an amenable mutation. The approved label includes 313 Fabry-causing mutations, which represent up to half of all patients with Fabry disease. The Company commenced commercial shipments of Galafold in the EU in the second quarter of 2016 and recognized net product sales of $5.0 million in 2016. Also in the pipeline, SD-101 is a product candidate in late-stage development, as a potential first-to-market therapy for the chronic, rare connective tissue disorder Epidermolysis Bullosa ("EB"). The Company is also leveraging its biologics and Chaperone-Advanced Replacement Therapy ("CHART™") platform technologies to develop novel ERT products for Pompe disease, Fabry disease, and potentially other lysosomal storage disorders ("LSDs"). The Company is also investigating preclinical and discovery programs in other rare and devastating diseases including cyclin-dependent kinase-like 5 ("CDKL5") deficiency. The Company believes that the platform technologies and advanced product pipeline uniquely position the Company at the forefront of advanced therapies to treat a range of devastating rare and orphan diseases. On December 21, 2016, the Company issued $250 million aggregate principal amount of 3.00% unsecured Convertible Senior Notes due 2023 (the "Convertible Notes"), in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the "Securities Act"). Interest is payable semiannually on June 15 and December 15 of each year, beginning on June 15, 2017. The Notes will mature on December 15, 2023, unless earlier repurchased, redeemed, or converted in accordance with their terms. The Notes are convertible at the option of the holders, under certain circumstances and during certain periods, into cash, shares of the Company's common stock, par value $0.01 per share ("Common Stock"), or a combination thereof. The net proceeds from the issuance of the Convertible Note offering were $243.1 million, after deducting fees and estimated expenses payable by the Company. In addition, the Company used approximately $13.5 million of the net proceeds from the issuance of the Convertible Notes to pay the cost of the capped call transactions ("Capped Call Confirmations") that the Company entered into in connection with the issuance of the Convertible Notes. For additional information, see "— Note 16. Debt Instruments and Related Party Transactions." In July 2016, the Company expanded its biologics pipeline with a new preclinical program for CDKL5 deficiency, a rare and devastating genetic neurological disease for which there is no currently approved treatment. The Company has obtained the rights and related intellectual property to a preclinical CDKL5 program through its acquisition of MiaMed, Inc ("MiaMed"). The aggregate value of the deal was approximately $89.5 million, which included an upfront payment of $6.5 million and Company stock, cash and potential milestones of up to $83.0 million. For additional information, see "— Note 3. Acquisitions". Beginning in April 2016 and through July 2016, the Company sold 15.0 million shares of Common Stock under an at-the-market ("ATM") equity program with Cowen and Company, LLC ("Cowen") acting as sales agent. Cowen was compensated at a fixed commission rate up to 3.0%. The ATM sales agreement resulted in net proceeds of $97.1 million, after Cowen's commission of $2.7 million and other expenses of $0.2 million. The Company has completed all sales under the ATM equity program. The Company had an accumulated deficit of approximately $779.6 million at December 31, 2016 and anticipates incurring losses through the fiscal year ending December 31, 2017 and beyond. The Company has been able to fund its operating losses to date through stock offering, debt issuances, and 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 the second half of 2018.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

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 consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions are eliminated in consolidation.

Foreign Currency Transactions

The functional currency for most of the Company's foreign subsidiaries is their local currency. For non-U.S. subsidiaries that transact in a functional currency other than the U.S. dollar, assets and liabilities are translated at current rates of exchange at the balance sheet date. Income and expense items are translated at the average foreign exchange rates for the period. Adjustments resulting from the translation of the financial statements of the Company's foreign operations into U.S. dollars are excluded from the determination of net income and are recorded in accumulated other comprehensive income, a separate component of equity.

The Company transacts business in various foreign countries and therefore, is subject to risk of foreign currency exchange rate fluctuations. As such, in June 2016, the Company entered into a forward contract to economically hedge transactional exposure associated with commitments arising from trade accounts payable denominated in a currency other than the functional currency of the respective operating entity. The Company does not designate this forward contract as a hedging instrument under applicable accounting guidance and, therefore, changes in fair value are recorded as other expense the Consolidated Statements of Operations.

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, 2016 and 2015.

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.

The Company is subject to credit risk from its accounts receivable related to its product sales of Galafold. The majority of the Company's accounts receivable at December 31, 2016 have arisen from product sales in Germany. The Company will periodically assess the financial strength of its customers to establish allowances for anticipated losses, if any. For accounts receivable that have arisen from named patient sales, the payment terms are predetermined and the Company evaluates the creditworthiness of each customer on a regular basis. To date, the Company has not incurred any credit losses.

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, which is typically upon shipment to the end-customer. Revenue is considered realizable and earned when persuasive evidence an arrangement exists, title to product and associated risk of loss has passed to the customer, the price is fixed or determinable, collection of the amounts due are reasonably assured and the Company has no further performance obligations.

Net Product Sales

The Company's net product sales consist solely of sales of Galafold for the treatment of Fabry disease in the EU. The Company has recorded revenue on sales where Galafold is available either on a commercial basis or through a reimbursed early access program. Orders for Galafold are generally received from pharmacies and the ultimate payor is typically a government authority.

The Company records revenue net of estimated third party discounts and rebates. Allowances are recorded as a reduction of revenue at the time revenues from product sales are recognized. These allowances are adjusted to reflect known changes in factors and may impact such allowances in the quarter those changes are known.

Collaboration Revenue

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;
	•	the identifiable benefit is separable from the existing relationship between the Company and its customer;
	•	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.

Inventories and Cost of Cost of Goods Sold

Until regulatory approval of Galafold, the Company expensed all manufacturing costs of Galafold as research and development expense. Upon regulatory approval, the Company began capitalizing costs related to the purchase and manufacture of Galafold.

Inventories are stated at the lower of cost or market determined by the first-in, first-out method. Inventories are reviewed periodically to identify slow-moving or obsolete inventory based on projected sales activity as well as product shelf-life. In evaluating the recoverability of inventories produced, the probability that revenue will be obtained from the future sale of the related inventory is considered and inventory value is written down for inventory quantities in excess of expected requirements. Expired inventory is disposed of and the related costs are recognized as cost of product sales in the consolidated statements of operations.

Cost of goods sold includes the cost of inventory sold, manufacturing and supply chain costs, product shipping and handling costs, provisions for excess and obsolete inventory, as well as royalties payable. A portion of the inventory available for sale was expensed as research and development costs prior to regulatory approval and as such the cost of goods sold and related gross margins are not necessarily indicative of future cost of goods sold and gross margin.

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 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 gain/(loss) on foreign currency transactions, 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

The Company's Cash Deferral Plan (the "Deferral Plan"), 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 are 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 the consolidated balance sheets.

Equity-based Compensation

At December 31, 2016, the Company had three equity-based employee compensation plans, which are described more fully in "— Note 9. Stockholders' Equity." The Company applies the fair value method of measuring equity-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 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. The fair value of the contingent consideration payable will be determined each period end and the resulting change will be 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.

Recent Accounting Pronouncements

In January 2017, the FASB issued ASU 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. To simplify the subsequent measurement of goodwill, ASU 2017-04 eliminates Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit's fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. In addition, income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. ASU 2017-04 also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. ASU 2017-04 should be applied on a prospective basis. The nature of and reason for the change in accounting principle should be disclosed upon transition. A public business entity that is a U.S. SEC filer should adopt ASU 2017-04 for its annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently assessing the impact that this standard will have on its consolidated financial statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This Accounting Standards Update clarifies the definition of a business. The amendments affect all companies and other reporting organizations that must determine whether they have acquired or sold a business. The amendments in this Update are effective for public companies for annual periods beginning after December 15, 2017, including interim periods within those periods. Early adoption is permitted under certain circumstances. The amendments should be applied prospectively as of the beginning of the period of adoption. The Company is currently assessing the impact that this standard will have on its consolidated financial statements.

In October 2016, the FASB issued ASU 2016-17, Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control. This Accounting Standards Update changes the evaluation of whether a reporting entity is the primary beneficiary of a variable interest entity by changing how a reporting entity that is a single decision maker of a variable interest entity treats indirect interests in the entity held through related parties that are under common control with the reporting entity. If a reporting entity satisfies the first characteristic of a primary beneficiary (such that it is the single decision maker of a variable interest entity), the amendments require that reporting entity, in determining whether it satisfies the second characteristic of a primary beneficiary, to include all of its direct variable interests in a variable interest entity and, on a proportionate basis, its indirect variable interests in a variable interest entity held through related parties, including related parties that are under common control with the reporting entity. The amendments in this Update are effective for public business entities for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company adopted this ASU in 2016 and the adoption did not have a material impact on its consolidated financial statements.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. This Accounting Standards Update requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments eliminate the exception for an intra-entity transfer of an asset other than inventory. The amendments in this Update are effective for public business entities for annual periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. Early adoption is permitted for all entities in the first interim period if an entity issues interim financial statements. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. We have not completed our review of the impact of this guidance and do not expect this new guidance to have a material impact on our Consolidated Financial Statements.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This Accounting Standards Update addresses the following eight specific cash flow issues including Debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination and separately identifiable cash flows and application of the predominance principle. The amendments in this ASU apply to all entities. The amendments in this Update are effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company adopted this ASU in 2016 and the adoption did not have a material impact on its consolidated financial statements.

In March 2016, the FASB issued ASU 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendments are intended to improve the accounting for employee share-based payments and affect all organizations that issue share-based payment awards to their employees. Several aspects of the accounting for share-based payment award transactions are simplified, including: (a) income tax consequences; (b) classification of awards as either equity or liabilities; and (c) classification on the statement of cash flows. For public companies, the amendments are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for any organization in any interim or annual period. The Company is currently assessing the impact that this standard will have on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This update requires the recognition of lease assets and lease liabilities on the balance sheet for all lease obligations and disclosing key information about leasing arrangements. This update requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous generally accepted accounting principles. This update will be effective for the Company for all annual and interim periods beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted for all public business entities and all nonpublic business entities upon issuance. The Company is currently assessing the impact that this standard will have on its consolidated financial statements.

In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory, which requires an entity to measure in scope inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments apply to inventory that is measured using first-in, first-out (FIFO) or average cost. The ASU is effective for public business entities for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. A reporting entity should apply the amendments prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. The Company is currently assessing the impact that this standard will have 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 Company adopted this ASU in 2016 and the adoption did not have a material impact on its consolidated financial statements.

In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers which along with amendments issued in 2015 and 2016, will replace substantially all current US GAAP guidance on this topic and eliminate industry-specific guidance. Early adoption of this standard is permitted but not before the original effective date for all annual periods and interim reporting periods beginning after December 15, 2017. The guidance permits two methods of adoption: full retrospective method (retrospective application to each prior reporting period presented) or modified retrospective method (retrospective application with the cumulative effect of initially applying the guidance recognized at the date of initial application and providing certain additional disclosures). To complete its assessment of the impact of the standard to its financial statements, the Company continues to assess all implications of this standard, method of adoption and related financial disclosures. Additionally, the Company continues to monitor modifications, clarifications and interpretations issued by the FASB that may impact its assessment.

Acquisitions	12 Months Ended
Acquisitions	Dec. 31, 2016
Acquisitions
Acquisitions	3. Acquisitions Acquisition of MiaMed, Inc. In July 2016, the Company entered into an Agreement and Plan of Merger (the "MiaMed Agreement") with MiaMed, Inc., ("MiaMed"). MiaMed is a pre-clinical biotechnology company focused on developing protein replacement therapy for CDKL5 and related diseases. Under the terms of the MiaMed Agreement, the former holders of MiaMed's capital stock received an aggregate of $6.5 million, comprised of (i) approximately $1.8 million in cash (plus MiaMed's cash and cash equivalents at closing and less any of MiaMed's unpaid third-party fees and expenses related to the transaction), and (ii) 825,603 shares of the Company's Common Stock. In addition, the Company also agreed to pay up to an additional $83.0 million in connection with the achievement of certain clinical, regulatory and commercial milestones, for a potential aggregate deal value of $89.5 million. The Company evaluated the transaction based on the guidance of Accounting Standard Codification ("ASC") 805, Business Combinations and concluded that it only acquired inputs and did not acquire any processes. The Company will need to develop its own processes in order to produce an output. Therefore, the Company accounted for the transaction as an asset acquisition and accordingly $6.5 million was expensed to research and development. Acquisition of Scioderm, Inc. In September 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 ASC 805 Business Combinations. 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 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 and updated timelines related to clinical development and anticipated approval assumptions as of December 31, 2016 without limitation, the $5 million milestone paid in the second quarter, and milestone payments projected for 2017 (See "— Note 10. Assets and Liabilities Measured at Fair Value", for additional discussion regarding fair value measurements of the contingent acquisition consideration payable). In April 2016, while the total clinical and regulatory approval milestone payments remain unchanged at $361 million, the allocation between the clinical and regulatory approval milestone payments were revised as follows: clinical milestones of up to $81 million and regulatory approval milestones of up to $280 million. The commercial milestone payments of up to $257 million remained unchanged. The Company determined the fair value of the contingent consideration to be $260.0 million at December 31, 2016, of which $56.1 million is payable in the next twelve months, resulting in an increase in the contingent consideration payable and related expense of approximately $7.3 million for the year ended December 31, 2016. The expense is recorded in the Consolidated Statement of Operations as the change within fair value of contingent consideration payable. For additional information, see "— Note 4. Goodwill and Intangible Assets." The purchase price allocation was subject to completion of the 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. 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. 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. 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. Key assumptions included a discount rate of 13.5% and various probability factors. This estimation was based on significant inputs that are not observable in the market, referred to as Level 3 inputs. Some of the more significant assumptions used in the valuation include (i) the probability and timing related to the achievement of certain developmental milestones and (ii) and the discount rate. As of December 31, 2016, 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 $9.7 million at December 31, 2016, all of which is payable beyond the next twelve months, resulting in an decrease in the contingent consideration payable and related gain of $0.5 million year ended December 31, 2016. The expense is recorded in the Consolidated Statement of Operations within the changes in fair value of contingent consideration line item. During the second quarter of 2016, the Company reached the first clinical milestone, which was the dosing of the first patient in a Phase 1 or 2 study. The milestone for this event was $6.0 million which was paid in Company stock during the second quarter of 2016, resulting in $6.1 million impact on stockholder's equity. For further information, see "— Note 4. Goodwill and Intangible Assets."

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2016

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, 2016:

	(in millions)
Balance at December 31, 2015	$	197.8
Change in goodwill		—

Balance at December 31, 2016	$	197.8

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, 2016:

	(in millions)
Balance at December 31, 2015	$	486.7
Change in IPR&D		—

Balance at December 31, 2016	$	486.7

Goodwill and intangible assets are 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 2016 annual impairment assessment, it was determined that the goodwill and intangible assets had not been impaired therefore there were no changes to the balances of goodwill and IPR&D in 2016.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Cash, Money Market Funds and Marketable Securities

12 Months Ended

Dec. 31, 2016

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, 2016, the Company held $187.0 million in cash and cash equivalents and $143.3 million of available-for-sale securities which are reported at fair value on the Company's Consolidated Balance Sheets. 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.

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.

The Company transacts business in various foreign countries and therefore, is subject to risk of foreign currency exchange rate fluctuations. As such, in June 2016 the Company entered into a forward contract to economically hedge transactional exposure associated with commitments arising from trade accounts payable denominated in a currency other than the functional currency of the respective operating entity. The Company does not designate these forward contracts as hedging instruments under applicable accounting guidance and, therefore, changes in fair value are recorded within other income (expense) in the Consolidated Statements of Operations, with the corresponding liability in current liabilities on the Consolidated Balance Sheet. For the year ended December 31, 2016, the Company recognized a loss of $0.3 million, related to the derivative instruments not designated as hedging instruments in other expense in the Consolidated Statements of Operations and the corresponding liability of $0.3 million is recorded as other current liability in the Consolidated Balance Sheets.

Cash and available for sale securities consisted of the following as of December 31, 2016 and December 31, 2015 (in thousands):

	As of December 31, 2016
	Cost		Unrealized Gain		Unrealized Loss			Fair Value
Cash balances	$	187,026	$	—	$	—		$	187,026
Corporate debt securities, current portion		74,564		2		(31	)		74,535
Commercial paper		68,258		132		—			68,390
Money market		350		—		—			350
Certificate of deposit		50		—		—			50

	$	330,248	$	134	$	(31	)	$	330,351


Included in cash and cash equivalents	$	187,026	$	—	$	—		$	187,026
Included in marketable securities		143,222		134		(31	)		143,325

Total cash and marketable securities	$	330,248		134	$	(31	)	$	330,351

	As of December 31, 2015
	Cost		Unrealized Gain		Unrealized Loss			Fair Value
Cash balances	$	69,485	$	—	$	—		$	69,485
Corporate debt securities, current portion		118,627		1		(154	)		118,474
Commercial paper		25,686		38		—			25,724
Certificate of deposit		350		—		—			350

	$	214,148	$	39	$	(154	)	$	214,033


Included in cash and cash equivalents	$	69,485	$	—	$	—		$	69,485
Included in marketable securities		144,663		39		(154	)		144,548

Total cash and marketable securities	$	214,148		39	$	(154	)	$	214,033

For the years ended December 31, 2016 and 2015, 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, 2016 and December 31, 2015 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 $58.7 million and $118.5 million as of December 31, 2016 and 2015, 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.

Inventories

12 Months Ended

Dec. 31, 2016

Inventories

Inventories

6. Inventories

Inventories consist of work in process and finished goods related to the manufacture of Galafold. The following table summarizes the components of inventories at December 31, 2016 (in thousands):

	December 31, 2016
Work-in-process	$	3,308
Finished goods		108

Total inventories	$	3,416

There were no inventories on-hand as of December 31, 2015. Inventory manufactured prior to commercialization was expensed to research and development. Inventories are reviewed periodically to identify slow-moving or obsolete inventory based on projected sales activity, as well as product shelf-life. In evaluating the recoverability of inventories produced, the Company considers the probability that revenue will be obtained from the future sale of the related inventory. Inventory becomes obsolete when it has aged past its shelf-life, cannot be recertified and is no longer usable or able to be sold, or the inventory has been damaged. In such instances, a full reserve is taken against such inventory. Expired inventory is disposed of and the related costs are recognized as cost of product sales in the consolidated statement of operations. There have been no write-downs of inventory from the time inventory was first capitalized.

Property and Equipment

12 Months Ended

Dec. 31, 2016

Property and Equipment

Property and Equipment

7. Property and Equipment

Property and equipment consist of the following (in thousands):

	December 31,
	2016			2015
Property and equipment consist of the following:
Computer equipment	$	3,511		$	5,075
Computer software		1,347			1,354
Research equipment		7,465			6,483
Furniture and fixtures		3,018			2,444
Leasehold improvements		6,970			4,175

		22,311			19,531
Less accumulated depreciation		(12,495	)		(13,353	)

	$	9,816		$	6,178

Depreciation expense was $3.2 million and $1.8 million for the years ended December 31, 2016 and 2015, respectively. As of December 31, 2016, $0.2 million of the depreciation expense was related to capital lease obligation. There were no capital lease obligations outstanding as of December 31, 2015.

Accounts Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2016

Accounts Payable and Accrued Expenses

Accounts Payable and Accrued Expenses

8. Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist of the following (in thousands):

	December 31,
	2016		2015
Accounts payable	$	12,905	$	16,477
Accrued professional fees		5,079		3,578
Accrued contract manufacturing & contract research costs		8,042		2,940
Accrued compensation and benefits		9,981		6,201
Accrued facility costs		1,740		1,321
Foreign currency forward contract		265		—
Capital lease, short term portion		283		—
Accrued other		2,713		1,699

	$	41,008	$	32,216

Stockholders' Equity

12 Months Ended

Dec. 31, 2016

Stockholders' Equity

Stockholders' Equity

9. Stockholders' Equity

Common Stock and Warrants

As of December 31, 2016, 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.

As discussed in "— Note 16. Debt Instruments and Related Party Transactions", on December 21, 2016, the Company issued $250 million aggregate principal amount of 3.0% unsecured Convertible Senior Notes due 2023 (the "Convertible Notes), in a private offering. The Notes will mature on December 15, 2023, unless earlier repurchased, redeemed, or converted in accordance with their terms. The Notes are convertible at the option of the holders, under certain circumstances and during certain periods, into cash, shares of the Company's common stock, par value $0.01 per share ("Common Stock"), or a combination thereof. Prior to the close of business on the business day immediately preceding September 15, 2023, the Notes are convertible at the option of the holders of the Notes only under certain conditions. On or after September 15, 2023, until the close of business on the second business day immediately preceding the maturity date, holders of the Notes may convert their Notes at their option at the conversion rate then in effect, irrespective of these conditions. The Company will settle conversions of the Notes by paying or delivering, as the case may be, cash, shares of Common Stock, or a combination of cash and shares of Common Stock, at the Company's election. The conversion rate will initially be 163.3987 shares of Common Stock per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $6.12 per share of Common Stock). The conversion rate is subject to customary adjustments upon the occurrence of certain events.

Beginning in April 2016 and through July 2016, the Company sold 15.0 million shares of Common Stock under an ATM equity program with Cowen and Company, LLC ("Cowen") acting as sales agent. Cowen was compensated at a fixed commission rate up to 3.0%. The ATM sales agreement resulted in net proceeds of $97.1 million, after Cowen's commission of $2.7 million and other expenses of $0.2 million. The Company has completed all sales under the ATM equity program.

As discussed in "— Note 16. Debt instruments and Related Party Transactions," the Company issued approximately 1.8 million and 1.3 million of warrants in February 2016 and June 2016, respectively. The closing balance of the warrants was $16.1 million as of December 31, 2016 and is recorded within equity on the Consolidated Balance Sheets.

As discussed in "— Note 3. Acquisitions, in July 2016, the Company entered into an Agreement and Plan of Merger (the "MiaMed Agreement") with MiaMed. Under the terms of the MiaMed Agreement, the former holders of MiaMed's capital stock received an aggregate of $6.5 million, comprised of (i) approximately $1.8 million in cash (plus MiaMed's cash and cash equivalents at closing and less any of MiaMed's unpaid third-party fees and expenses related to the transaction), and (ii) 825,603 shares of the Company's Common Stock. In addition, the Company also agreed to pay up to an additional $83.0 million in connection with the achievement of certain clinical, regulatory and commercial milestones, for a potential aggregate deal value of $89.5 million.

As discussed in "— Note 3. Acquisitions, 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, the Company 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 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

The Company's Deferral Plan, (the "Deferral Plan") 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, 2016 were approximately $1.5 million, as compared to $0.7 million on December 31, 2015 and are included in other long-term liabilities. Deferral Plan assets as of December 31, 2016 were $1.5 million as compared to $0.7 million as of December 31, 2015 and are classified as trading securities. The Deferred Plan assets are recorded at fair value with changes in the investments' fair value recognized in AOCI in the period they occur. The income from investment for the year ended December 31, 2016 and 2015 was $34 thousand and $17 thousand respectively. Unrealized gain approximated $32 thousand for the year ended December 31, 2016, as compared to unrealized loss of $50 thousand for the year ended December 31, 2015.

Equity Incentive Plans

The Company's Equity Incentive Plans consist of the Amended and Restated 2007 Equity Incentive Plan (the "Plan") and the 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, 2016, the Company has reserved up to 12,630,511 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,
	2016			2015			2014
Expected stock price volatility		81.3	%		75.9	%		81.3	%
Risk free interest rate		1.5	%		1.7	%		1.9	%
Expected life of options (years)		6.25			6.25			6.25
Expected annual dividend per share	$	0.00		$	0.00		$	0.00

The weighted average grant-date fair value per share of options granted during 2016, 2015 and 2014 were $5.28, $7.51 and $2.12, 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, 2013		9,041.1		$	5.65
Granted		2,993.1		$	2.99
Exercised		(965.6	)	$	3.80
Forfeited		(1,047.9	)	$	5.76

Options outstanding, December 31, 2014		10,020.7		$	5.02
Granted		3,917.2		$	11.61
Exercised		(2,070.3	)	$	5.43
Forfeited		(138.4	)	$	7.76

Options outstanding, December 31, 2015		11,729.2		$	7.11
Granted		5,114.1		$	7.67
Exercised		(723.1	)	$	4.20
Forfeited		(622.7	)	$	8.62

Options outstanding, December 31, 2016		15,497.5		$	7.37		7.3 years	$	7.8


Vested and unvested expected to vest, December 31, 2016		(14,593.7	)	$	7.31		7.2 years	$	7.7
Exercisable at December 31, 2016		7,545.3		$	6.57		5.8 years	$	5.8

The aggregate intrinsic value of options exercised during the years ended December 31, 2016, 2015 and 2014 was $2.6 million, $14.7 million and $2.8 million respectively. Cash proceeds from stock options exercised during the years ended December 31, 2016, 2015, and 2014 were $3.0 million, $11.2 million, and $3.7 million, respectively. As of December 31, 2016, the total unrecognized compensation cost related to non-vested stock options granted was $33.7 million and is expected to be recognized over a weighted average period of 2.8 years.

Restricted Stock Units

RSUs awarded under the Plan are generally subject to graded vesting and are contingent on an employee's continued service. 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, 2016 is as follows:

	Number of Share			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		955.0		$	2.28
Granted		366.0		$	12.63
Vested		(842.5	)	$	—
Forfeited		—		$	—

Non-vested units as of December 31, 2015		478.5		$	10.38
Granted		582.7		$	6.21
Vested		(281.9	)	$	8.73
Forfeited		(34.9	)	$	7.71

Non-vested units as of December 31, 2016		744.4		$	7.86		2.62	$	—

For the year ended December 31, 2016, 0.3 million of the RSUs vested and all non-vested units are expected to vest over their normal term. As of December 31, 2016, there was $4.2 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 2.62 years.

On December 30, 2016, the Compensation Committee approved a form of Performance-Based Restricted Stock Unit Award Agreement (the "Performance-Based RSU Agreement"), to be used for performance-based RSUs granted to participants under the Amended and Restated Amicus Therapeutics, Inc. 2007 Equity Incentive Plan, including named executive officers. Awards under the form of Performance-Based RSU Agreement will vest based on the Company meeting specified performance criteria. Vesting of the RSUs is generally subject to the participant's continuous service with the Company through a specified date. As of December 31, 2016 there were no RSUs issued under the Performance-Based RSU Agreement.

Compensation Expense Related to Equity Awards

The following table summarizes the equity-based compensation expense recognized in the statements of operations (in thousands):

	Years Ended December 31,
	2016		2015		2014
Equity compensation expense recognized in:
Research and development expense	$	8,071	$	4,600	$	2,703
Selling, general and administrative expense		9,433		5,372		3,305

Total equity compensation expense	$	17,504	$	9,972	$	6,008

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Topic 210
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Subparagraph (SX 210.3-04)
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Assets and Liabilities Measured at Fair Value

12 Months Ended

Dec. 31, 2016

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.

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, 2016 are identified in the following table (in thousands):

	Level 2		Total
Commercial paper	$	68,390	$	68,390
Corporate debt securities		74,535		74,535
Money market funds		1,829		1,829

	$	144,754	$	144,754

	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	269,722	$	269,722
Derivative liability		265		—		265
Deferred compensation plan liability		1,479		—		1,479

	$	1,744	$	269,722	$	271,466

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, 2015 are identified in the following table (in thousands):

	Level 2		Total
Commercial paper		25,724		25,724
Corporate debt securities		118,474		118,474
Certificate of deposit		350		350
Market exchanged mutual funds		658		658

	$	145,206	$	145,206

	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	274,077	$	274,077
Deferred compensation plan liability		667		—		667

	$	667	$	274,077	$	274,744

See "— Note 16. Debt Instruments and Related Party Transactions" for the carrying amount and estimated fair value of the Company's Convertible Notes due in 2023. The Company did not have any Level 3 assets as of December 31, 2016 or 2015.

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, 2016. No transfers of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the year ended December 31, 2016.

Contingent Consideration Payable

The contingent consideration payable resulted from the acquisitions of Scioderm and Callidus, as discussed in "— Note 3. Acquisitions." The 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 is performed quarterly. Gains and losses are included in the statement of operations.

As discussed in "— Note 3. Acquisitions," on July 5, 2016, the Company entered into the MiaMed Agreement with MiaMed. MiaMed is a pre-clinical biotechnology company focused on developing protein replacement for CDKL5 and related diseases. Under the terms of the MiaMed Agreement, the Company agreed to pay up to an additional $83.0 million in connection with the achievement of certain clinical, regulatory and commercial milestones, for a potential aggregate deal value of $89.5 million. The MiaMed Agreement was accounted for as an asset acquisition and as such the Company determined that a liability for future milestone payments is not required to be recorded until the actual contingencies are met and will be recorded to research and development expenses when the contingency is resolved.

The contingent consideration payable for Scioderm and Callidus has been classified as a Level 3 recurring 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, including expenses related to CDKL5.

The following significant unobservable inputs were used in the valuation of the contingent consideration payable to former Scioderm stockholders:

Contingent Consideration Liability	Fair value as of December 31, 2016	Valuation Technique	Unobservable Input	Range
			Discount rate	0.62% - 3.8%
Clinical and regulatory milestones	$237.2 million	Probability weighted discounted cash flow	Probability of achievement of milestones	66.5% - 100.0%
			Projected year of payments	2017-2019
			Revenue volatility	58%
			Probability of achievement of milestones	66.5%
Revenue-based milestones	$22.8 million	Monte Carlo	Discount rate	1.47% - 2.55%
			Projected year of payments	2019-2029

The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Callidus for the ATB-200 Pompe program:

Contingent Consideration Liability	Fair value as of December 31, 2016	Valuation Technique	Unobservable Input	Range
			Discount rate	12.5%
Clinical and regulatory milestones	$9.3 million	Probability weighted discounted cash flow	Probability of achievement of milestones	30.4%-42.8%
			Projected year of payments	2018-2022

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, 2016 and 2015, respectively (in thousands):

	Year ended December 31,
	2016			2015
Balance, beginning of the period	$	274,077		$	10,700
Additions, from business acquisitions		—			259,000
Payment of contingent consideration in cash		(5,000	)		—
Payment of contingent consideration in stock		(6,115	)		—
Unrealized change in fair value change during the period, included in Statement of Operations		6,760			4,377

Balance, end of the period	$	269,722		$	274,077

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 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. 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.

Foreign Currency Exchange Rate Exposure

The Company transacts business in various foreign countries and therefore, is subject to risk of foreign currency exchange rate fluctuations. As such, in June 2016, the Company entered into a forward contract to economically hedge transactional exposure associated with commitments arising from trade accounts payable denominated in a currency other than the functional currency of the respective operating entity. The Company did not designate this forward contract as a hedging instrument under applicable accounting guidance and, therefore, the change in fair value is recorded in the Consolidated Statements of Operations. The forward contract settles in monthly installments with the final installment settlement in June 2017.

There were no outstanding forward contracts at December 31, 2015.

For the year ended December 31, 2016, the Company recognized a loss of $265 thousand, related to the derivative instruments not designated as hedging instruments in the Consolidated Statements of Operations and the corresponding liability of $265 thousand is recorded as other current liability in the Consolidated Balance Sheets.

The impact of gains and losses on foreign exchange contracts not designated as hedging instruments related to changes in the fair value of assets and liabilities denominated in foreign currencies are generally offset by net foreign exchange gains and losses, which are also included on the Consolidated Statements of Operations in other income (expense), net for all periods presented. When the Company enters into foreign exchange contracts not designated as hedging instruments to mitigate the impact of exchange rate volatility in the translation of foreign earnings, gains and losses will generally be offset by fluctuations in the U.S. Dollar translated amounts of each account within the Consolidated Statements of Operations in current and/or future periods.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2016
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 2016 or 2015. The Company's total contribution to the 401(k) Plan was $1.2 million, $0.9 million and $0.6 million for the years ended December 31, 2016, 2015 and 2014, respectively.

Leases

12 Months Ended

Dec. 31, 2016

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, 2016:

Location	Approximate Square Feet		Use	Lease expiry date
Cranbury, New Jersey		90,000	Office and laboratory	September 2025
Durham, North Carolina		5,603	Office	June 2018
Buckinghamshire, United Kingdom		9,821	Office	September 2020
Munich, Germany		4,316	Office	April 2017

In addition to the above, we also maintain small offices in the Italy, France, Netherlands and Spain. 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, 2016, aggregate annual future minimum lease payments under these leases are as follows:

(in thousands)		2017			2018			2019			2020			2021 and beyond			Total
Minimum lease payments		$	2,666		$	2,483		$	2,421		$	2,349		$	10,537		$	20,456

Rent expense, including fees for utilities and common area maintenances for the years ended December 31, 2016, 2015 and 2014 were $3.5 million, $2.6 million and $2.4 million, respectively.

Capital Leases

In 2016, the Company purchased equipment of approximately $0.9 million through financing arrangements. These financing arrangements include interest of approximately 0.2-5.7%, and lease terms of 36-48 months.

At December 31, 2016, aggregate annual future minimum lease payments under these leases, including interest, are as follows (in thousands):

Years ending December 31:
2017	$	355
2018		355
2019		134
2020		—
2021 and beyond		—

Total principal obligation	$	844

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Taxes

Income Taxes

13. Income Taxes

For financial reporting purposes, income (loss) before income taxes includes the following components (in thousands):

	Years Ended December 31,
	2016			2015			2014
United States	$	(174,913	)	$	(123,697	)	$	(70,030	)
Foreign		(28,868	)		(8,421	)		(9	)

Total	$	(203,781	)	$	(132,118	)	$	(70,039	)

A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 31, 2016, 2015 and 2014 are as follows:

	Years Ended December 31,
	2016			2015			2014
Statutory rate		(34	)%		(34	)%		(34	)%
State taxes, net of federal benefit		(5	)		(5	)		(4	)
Permanent adjustments		3			2			1
R&D credit		(3	)		(3	)		(4	)
Foreign income tax rate differential		2			1			—
Other		(1	)		2			1
Valuation allowance		36			37			38

Net		(2	)%		(0	)%		(2	)%

The Company recognized a tax benefit of $1.1 million in connection with the sale of net operating losses and research and development credits in the New Jersey Transfer Program for the year ended December 31, 2014. There were no sales of net operating losses and research and development credits for the years ended December 31, 2016 and 2015.

The Company recorded an income tax benefit of $3.7 million in the Consolidated Statement of Operations for the year ended December 31, 2016. The benefit was primarily from $2.7 million in income tax benefit in connection with the reduction in state tax rates in North Carolina, and $1.2 million from reduction in its valuation allowance to reflect the income tax associated with the gain on foreign currency translation recorded in the Consolidated Statement of Comprehensive Loss for the year ended December 31, 2016.

The Company did not recognize interest or penalties related to income tax during the period ended December 31, 2016 and did not accrue for interest or penalties as of December 31, 2016. The Company does not have an accrual for uncertain tax positions as of December 31, 2016. Tax returns for all years 2009 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,
	2016			2015
Non-current deferred tax assets
Intellectual property	$	95,956		$	—
Amortization/depreciation		1,781			2,657
Research tax credit		32,851			27,170
Net operating loss carry forwards		253,661			159,889
Deferred revenue		14,281			14,281
Non-cash stock issue		11,649			6,767
Others		3,358			2,964

Gross deferred tax assets		413,537			213,728
Deferred tax liability related to business acquisition		(173,771	)		(176,219	)
Deferred tax liability related to royalty payable		(96,829	)		—
Deferred tax liability related to convertible notes		(29,845	)		—

Total net deferred tax asset		113,092			37,509
Less valuation allowance		(286,863	)		(213,728	)

Net deferred tax assets (liability)	$	(173,771	)	$	(176,219	)

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, 2016 and 2015, the Company recorded valuation allowances of $286.9 million and $213.7 million, respectively, representing an increase in the valuation allowance of $73.2 million in 2016 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, 2016, the Company had federal, state, and foreign net operating loss carry forwards ("NOLs") of approximately $637 million, $623 million, and $40 million respectively. The federal carry forward will expire in 2029 through 2036. 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 2016 will expire in 2029 through 2036. The foreign NOLs have indefinite expiration. 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 2016 and determined that in 2016, 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 $4.6 million associated with the exercise of stock options will be recorded in additional paid-in capital when the associated net operating loss is recognized.

Licenses	12 Months Ended
Licenses	Dec. 31, 2016
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 Mt. Sinai School of Medicine ("MSSM") of New York University. Under this agreement, to date, the Company has paid no upfront or annual license fees and there are no milestone or future payments other than royalties on net sales. 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 the combination therapy, subject to any patent term extension that may be granted. 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 the Company 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, in 2016, the Company incurred $0.1 million of royalty expense under the agreement with MSSM. 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

12 Months Ended

Dec. 31, 2016

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 earlier 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. In the second half of 2016, the Company recognized approximately $0.5 million under the revised agreement with GSK.

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.

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.

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.

Debt Instruments and Related Party Transactions

12 Months Ended

Dec. 31, 2016

Debt Instruments and Related Party Transactions

Debt Instruments and Related Party Transactions

16. Debt Instruments and Related Party Transactions

October 2015 and February 2016 Notes and Warrants Purchase Agreement

In October 2015, the Company entered into the October 2015 Purchase Agreement with Redmile, who beneficially owned approximately 6.7% of the Common Stock as of December 31, 2015, 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 contained two installments, the first $15.0 million in October 2017 and the balance $35.0 million in October 2020. Interest was payable at 4.1% on a monthly basis over the term of the loan. 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 relative fair value of the warrants and the debt discount as related to the October 2015 purchase agreement was determined to be $8.8 million.

This Purchase Agreement was modified in February 2016 when 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 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 paid Redmile any unpaid interest accrued thereunder. Pursuant to the February 2016 agreement, at closing, it sold, on a private placement basis (a) $50.0 million aggregate principal amount of unsecured promissory notes ("Initial Notes") and (b) five year warrants to purchase up to 37 shares of the Company's Common Stock for every $1,000 of the principal amount of Initial Notes purchased ("Initial Warrants"), for an aggregate of up to 1,850,000 shares of Common Stock issuable under the Initial Warrants. The payment terms contained two installments, the first $15.0 million in October 2017 and the balance $35.0 million in October 2021. The interest rate was 3.875% and payable upon of maturity. This transaction was accounted for as a debt modification in accordance with ASC 470-50. The incremental fair value between the warrants that were cancelled and the February issued warrants of $3.5 million was recorded as additional unamortized debt discount on the balance sheet and added to the prior warrant balance within equity.

The Notes mentioned above were cancelled in December 2016. For more details, refer to section December 2016 Note Purchase Agreement below in this footnote.

June 2016 Amended Purchase Agreement

In June 2016, following the marketing approval for migalastat in Europe, the Company entered into the Amended Purchase Agreement with Redmile. Such amendment joined GCM to the February 2016 Purchase Agreement. Pursuant to the Amended Purchase Agreement, the Company sold an additional $30 million unsecured promissory notes and five year warrants to purchase up to purchase up to 42 shares of our Common Stock, par value $0.01 per share for every $1,000 of the principal amount of additional notes purchased, for an aggregate of up to 1,260,000 shares of Common Stock issuable from the additional warrants. The payment was due in October 2021. The interest rate was 3.875% and payable upon of maturity. The Notes mentioned above were cancelled in December 2016. For more details, refer to section December 2016 Note Purchase Agreement below in this footnote.

December 2016 Note Purchase Agreement

On December 15, 2016, the Company entered into a Note Purchase Agreement ("Note Purchase Agreement") with GCM and RedMile, pursuant to which the Company agreed to prepay all outstanding principal and accrued and unpaid interest on the notes issued by the Company and held by GCM and Redmile. Such prepayment was made on December 21, 2016. The Note Purchase Agreement did not cancel the warrants, under the Amended Purchase Agreement. The net loss on extinguishment of the debt was $13.3 million and is included as loss on extinguishment in the Consolidated Statement of Operations for the year ended December 31, 2016.

2016 Convertible Debt

On December 21, 2016, the Company issued at par value $250 million aggregate principal amount of unsecured Convertible Senior Notes due 2023 (the "Convertible Notes"), which included the exercise in full of the $25 million over-allotment option granted to the initial purchasers of the Notes, in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act. Interest is payable semiannually on June 15 and December 15 of each year, beginning on June 15, 2017. The Notes will mature on December 15, 2023, unless earlier repurchased, redeemed, or converted in accordance with their terms. The Notes are convertible at the option of the holders, under certain circumstances and during certain periods, into cash, shares of the Company's common stock or a combination thereof and may be settled as described below. The net proceeds from the Note Offering were $243.1 million, after deducting fees and estimated expenses payable by the Company. In addition, the Company used approximately $13.5 million of the net proceeds from the issuance of the Convertible Notes to pay the cost of the capped call transactions ("Capped Call Confirmations") that the Company entered into in connection with the issuance of the Convertible Notes.

The Convertible Notes are governed by an indenture dated December 21, 2016 (the "Indenture") by and between Amicus and Wilmington Trust, National Association, as trustee.

The Convertible Notes are initially convertible into approximately 40,849,675 shares of the Company's common stock under certain circumstances prior to maturity at a conversion rate of 163.3987 shares per $1,000 principal amount of Convertible Notes, which represents a conversion price of approximately $6.12 per share of Common Stock, subject to adjustment under certain conditions. Holders may convert their Convertible Notes at their option at specified times prior to the maturity date of December 15, 2023, only if:


	•	during any fiscal quarter commencing after March 31, 2017, if the last reported sale price of the Company's common stock for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is equal to or more than 130% of the conversion price of the Convertible Notes on the last day of such preceding fiscal quarter;
	•	a Holder submits its Convertible Notes for conversion during the five business day period following any five consecutive trading day period in which the trading price for the Convertible Notes, per $1,000 principal amount of the Convertible Notes, for each such trading day was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate of the Convertible Notes on such date; or
	•	the Company issues to all or substantially all of the holders of common stock rights options or warrants entitling then them for a period of not more than 60 calendar days after the date of such issuance to subscribe for or purchase shares of the Common Stock, at a price per share less than the average of the Last Reported Sale Prices of the Common Stock for the 10 consecutive Trading Day period ending on, and including, the Trading Day immediately preceding the date of announcement of such issuance or distributes to all or substantially all holders of the Common Stock the Company's assets, debt securities or rights to purchase the Company's securities which distribution has a per share value of exceeding 10% of the Last Reported Sale Price of the Common Stock on the Trading Day immediately preceding the date of announcement of such distribution
	•	the Company enters into specified corporate transactions.
	•	the Company has had a call for redemption, the holder can convert up until the second trading day immediately preceding the redemption date

The Convertible Notes will be convertible, at the option of the note holders, regardless of whether any of the foregoing conditions have been satisfied, on or after September 15, 2023 at any time prior to the close of business on the second scheduled trading day immediately preceding the stated maturity date of December 15, 2023.

Upon the occurrence of a make-whole fundamental change or if the Company call all or any portion of the Convertible Notes for redemption prior to July 1, 2020, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Convertible Notes in connection with such make-whole fundamental change or during the related redemption period.

Upon conversion, the Company may pay cash, shares of the Company's common stock or a combination of cash and stock, as determined by the Company in its discretion.

The Company accounts for the Convertible Notes as a liability and equity component where the carrying value of the liability component will be valued based on a similar instrument. In accounting for the issuance of the Convertible Notes, the Company separated the Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the Convertible Notes as a whole. The excess of the principal amount of the liability component over its carrying amount, referred to as the debt discount, is amortized to interest expense over the seven-year term of the Convertible Notes. The equity component is not re-measured as long as it continues to meet the conditions for equity classification.

In accounting for the issuance of the Convertible Notes, the Company separated the Convertible Notes into liability and equity components based on their relative values. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the Convertible Notes. The difference between the principal amount of the Convertible Notes and the liability component represents the debt discount, which is recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and amortized to interest expense using the effective interest method over the seven-year term of the Convertible Notes. The equity component of the Convertible Notes of approximately $88.3 million is included in additional paid-in capital in the Consolidated Balance Sheets and is not remeasured as long as it continues to meet the conditions for equity classification. Additionally, the Company recorded a deferred tax liability of $29.8 million in relation to the Convertible Notes.

The Company incurred transaction costs of approximately $7.5 million, including approximately $6.9 million that was paid from the gross proceeds of the Convertible Notes offering. In accounting for the transaction costs, the Company allocated the total amount incurred to the liability and equity components using the same proportions as the proceeds from the Convertible Notes. Transaction costs attributable to the liability component were recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and amortized to interest expense over the seven-year term of the Convertible Notes. Transaction costs attributable to the equity component were netted with the equity component in additional-paid-in-capital.

The Convertible Notes consist of the following as of December 31, 2016:

Liability component	(In thousands)
Principal	$	250,000
Less: debt discount (1)		(90,807	)
Less: deferred financing (1)		(4,729	)

Net carrying value of the debt	$	154,464


(1)	Included in the Consolidated Balance Sheets within Convertible Senior Notes (due 2023) and amortized to interest expense over the remaining life of the Convertible Senior Notes using the effective interest rate method.

The fair value of the debt at December 31, 2016 was approximately $258.8 million.

The following table sets forth total interest expense recognized related to the Convertible Notes for the year ended December 31, 2016:

Components	(In thousands)
Contractual interest expense	$	208
Amortization of deferred financing		26
Amortization of debt discount		248
Total	$	482

Effective interest rate of the liability component		10.85	%

The Capped Call Confirmations of $13.5 million are expected generally to reduce the potential dilution to the Common Stock upon any conversion of the Convertible Notes and/or offset the cash payments the Company is required to make in excess of the principal amount upon conversion of the Notes in the event that the market price of the Common Stock is greater than the strike price of the Capped Call Confirmations (which initially corresponds to the initial conversion price of the Convertible Notes and is subject to certain adjustments under the terms of the Capped Call Confirmations), with such reduction and/or offset subject to a cap based on the cap price of the Capped Call Confirmations. The Capped Call Confirmations have an initial cap price of $7.20 per share, which represents a premium of approximately 50% over the closing price of the Company's Common Stock on The NASDAQ Global Market on December 15, 2016, and is subject to certain adjustments under the terms of the Capped Call Confirmations. The Capped Call Confirmations will cover, subject to anti-dilution adjustments substantially similar to those applicable to the Convertible Notes, the number of shares of Common Stock that will underlie the Convertible Notes. The Capped Call Confirmations do not meet the criteria for separate accounting as a derivative as they are indexed to the Company's Common Stock. The premiums paid for the Capped Call Confirmations have been included as a net reduction to additional paid-in capital.

Earnings per Share

12 Months Ended

Dec. 31, 2016

Earnings per Share

Earnings per Share

17. 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,
Historical	2016			2015			2014
Numerator:
Net loss attributable to common stockholders	$	(200,042	)	$	(132,118	)	$	(68,926	)


Denominator:
Weighted average common shares outstanding—basic and diluted		134,401,588			109,923,815			74,444,157

Dilutive common stock equivalents would include the dilutive effect of common stock options, convertible debt units, RSUs 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. For the year ended 2016 there was 40.9 million potential common shares outstanding as a result of the convertible debt that was excluded from the diluted net loss per share calculation because their effect would have been anti-dilutive.

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,
	2016		2015		2014
Options to purchase common stock		15,528		11,729		10,021
Convertible debt		40,850		—		—
Outstanding warrants, convertible to common stock		3,110		1,350		1,600
Unvested restricted stock units		744		479		955

Total number of potentially issuable shares		60,232		13,558		12,576

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2016
Commitments and Contingencies
Commitments and Contingencies	Note 18. 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. On May 26, 2016, the Court consolidated these lawsuits into a single action and appointed a lead plaintiff. The lead plaintiff filed a Consolidated Amended Class Action Complaint on July 11, 2016. On August 25, 2016, the defendants filed a motion to dismiss in response to the Consolidated Amended Class Action Complaint. This motion to dismiss was fully briefed on October 28, 2016. Lead plaintiff and defendants have reached an agreement in principal to fully and finally settle all claims asserted in the Consolidated Amended Class Action Complaint. The settlement is immaterial to the Company's consolidated financial statements and is subject to, among other things, documentation and court approval. The settlement amount is expected to be fully covered under insurance. 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, against the individuals who serve on the Amicus Board of Directors. Amicus itself was named as a nominal defendant. The derivative lawsuit alleged claims for breach of state law fiduciary duties, waste of corporate assets, and unjust enrichment based on allegedly false and misleading statements made by Amicus related to the regulatory approval path for migalastat HCl. On February 19, 2016, the complaint was dismissed by the Court and plaintiffs have not refiled. On or about March 3, 2016, a derivative lawsuit was filed by an Amicus shareholder purportedly on Amicus' behalf in the Superior Court of New Jersey, Middlesex County, Chancery Division, against various officers and directors of the Company. Amicus itself is named as a nominal defendant. The derivative lawsuit alleges similar facts and circumstances as the three purported securities class action lawsuits described above and further alleges claims for breach of state law fiduciary duties, waste of corporate assets, unjust enrichment, abuse of control, and gross mismanagement based on 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. On February 7, 2017, the complaint was dismissed by the Court without prejudice. These lawsuits 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 we could be forced to expend significant resources in the defense of these suits, and we may not prevail.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events
Subsequent Events	19. Subsequent Events The Company evaluated events that occurred subsequent to December 31, 2016 and found there were no material recognized or non-recognized subsequent events during this period.

Selected Quarterly Financial Data (Unaudited - in thousands except per share data)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Data (Unaudited - in thousands except per share data)

Selected Quarterly Financial Data (Unaudited - in thousands except per share data)

20. Selected Quarterly Financial Data (Unaudited—in thousands except per share data)

	Quarters Ended
	March 31			June 30			September 30			December 31
2016
Net loss	$	(43,691	)	$	(51,050	)	$	(46,654	)	$	(58,647	)
Basic and diluted net loss per common share (1)		(0.35	)		(0.40	)		(0.33	)		(0.41	)
2015
Net loss	$	(24,288	)	$	(27,133	)	$	(37,800	)	$	(42,897	)
Basic and diluted net loss per common share (1)		(0.25	)		(0.27	)		(0.32	)		(0.34	)


(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 Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Summary of Significant Accounting Policies

Basis of Presentation

Consolidation

The consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions are eliminated in consolidation.

Foreign Currency Transactions

Use of 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.

Concentration of Credit Risk

Property and Equipment

Revenue Recognition

Net Product Sales

Collaboration Revenue


	•	a payment for an identifiable benefit;
	•	the identifiable benefit is separable from the existing relationship between the Company and its customer;
	•	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

Inventories and Cost of Cost of Goods Sold

Fair Value Measurements

Contingent Liabilities

Research and Development Costs

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 debt.

Income Taxes

Other Comprehensive Income/ (Loss)

Leases

Nonqualified Cash Deferral Plan

Equity-based Compensation

Loss per Common Share

Dividends

Segment Information

Business Combinations

Contingent Consideration Payable

Intangible Assets and Goodwill

Recent Accounting Pronouncements

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets

Schedule of changes in goodwill

	(in millions)
Balance at December 31, 2015	$	197.8
Change in goodwill		—

Balance at December 31, 2016	$	197.8

Schedule of changes in IPR&D

	(in millions)
Balance at December 31, 2015	$	486.7
Change in IPR&D		—

Balance at December 31, 2016	$	486.7

Cash, Money Market Funds and Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2016

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, 2016 and December 31, 2015 (in thousands):

	As of December 31, 2016
	Cost		Unrealized Gain		Unrealized Loss			Fair Value
Cash balances	$	187,026	$	—	$	—		$	187,026
Corporate debt securities, current portion		74,564		2		(31	)		74,535
Commercial paper		68,258		132		—			68,390
Money market		350		—		—			350
Certificate of deposit		50		—		—			50

	$	330,248	$	134	$	(31	)	$	330,351


Included in cash and cash equivalents	$	187,026	$	—	$	—		$	187,026
Included in marketable securities		143,222		134		(31	)		143,325

Total cash and marketable securities	$	330,248		134	$	(31	)	$	330,351

	As of December 31, 2015
	Cost		Unrealized Gain		Unrealized Loss			Fair Value
Cash balances	$	69,485	$	—	$	—		$	69,485
Corporate debt securities, current portion		118,627		1		(154	)		118,474
Commercial paper		25,686		38		—			25,724
Certificate of deposit		350		—		—			350

	$	214,148	$	39	$	(154	)	$	214,033


Included in cash and cash equivalents	$	69,485	$	—	$	—		$	69,485
Included in marketable securities		144,663		39		(154	)		144,548

Total cash and marketable securities	$	214,148		39	$	(154	)	$	214,033

Inventories (Tables)

12 Months Ended

Dec. 31, 2016

Inventories

Schedule of inventories for the period

The following table summarizes the components of inventories at December 31, 2016 (in thousands):

	December 31, 2016
Work-in-process	$	3,308
Finished goods		108

Total inventories	$	3,416

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property and Equipment

Schedule of property and equipment

Property and equipment consist of the following (in thousands):

	December 31,
	2016			2015
Property and equipment consist of the following:
Computer equipment	$	3,511		$	5,075
Computer software		1,347			1,354
Research equipment		7,465			6,483
Furniture and fixtures		3,018			2,444
Leasehold improvements		6,970			4,175

		22,311			19,531
Less accumulated depreciation		(12,495	)		(13,353	)

	$	9,816		$	6,178

Accounts Payable and Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2016

Accounts Payable and Accrued Expenses

Schedule of accounts payable and accrued expenses

Accounts payable and accrued expenses consist of the following (in thousands):

	December 31,
	2016		2015
Accounts payable	$	12,905	$	16,477
Accrued professional fees		5,079		3,578
Accrued contract manufacturing & contract research costs		8,042		2,940
Accrued compensation and benefits		9,981		6,201
Accrued facility costs		1,740		1,321
Foreign currency forward contract		265		—
Capital lease, short term portion		283		—
Accrued other		2,713		1,699

	$	41,008	$	32,216

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity

Schedule of fair value weighted-average assumptions

	Years Ended December 31,
	2016			2015			2014
Expected stock price volatility		81.3	%		75.9	%		81.3	%
Risk free interest rate		1.5	%		1.7	%		1.9	%
Expected life of options (years)		6.25			6.25			6.25
Expected annual dividend per share	$	0.00		$	0.00		$	0.00

Summary of 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, 2013		9,041.1		$	5.65
Granted		2,993.1		$	2.99
Exercised		(965.6	)	$	3.80
Forfeited		(1,047.9	)	$	5.76

Options outstanding, December 31, 2014		10,020.7		$	5.02
Granted		3,917.2		$	11.61
Exercised		(2,070.3	)	$	5.43
Forfeited		(138.4	)	$	7.76

Options outstanding, December 31, 2015		11,729.2		$	7.11
Granted		5,114.1		$	7.67
Exercised		(723.1	)	$	4.20
Forfeited		(622.7	)	$	8.62

Options outstanding, December 31, 2016		15,497.5		$	7.37		7.3 years	$	7.8


Vested and unvested expected to vest, December 31, 2016		(14,593.7	)	$	7.31		7.2 years	$	7.7
Exercisable at December 31, 2016		7,545.3		$	6.57		5.8 years	$	5.8

Summary of non-vested Restricted Stock Units activity

	Number of Share			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		955.0		$	2.28
Granted		366.0		$	12.63
Vested		(842.5	)	$	—
Forfeited		—		$	—

Non-vested units as of December 31, 2015		478.5		$	10.38
Granted		582.7		$	6.21
Vested		(281.9	)	$	8.73
Forfeited		(34.9	)	$	7.71

Non-vested units as of December 31, 2016		744.4		$	7.86		2.62	$	—

Summary of the equity-based compensation expense recognized in the statements of operations

The following table summarizes the equity-based compensation expense recognized in the statements of operations (in thousands):

	Years Ended December 31,
	2016		2015		2014
Equity compensation expense recognized in:
Research and development expense	$	8,071	$	4,600	$	2,703
Selling, general and administrative expense		9,433		5,372		3,305

Total equity compensation expense	$	17,504	$	9,972	$	6,008

Assets and Liabilities Measured at Fair Value (Tables)

12 Months Ended

Dec. 31, 2016

Summary of assets and liabilities subject to fair value measurements

	Level 2		Total
Commercial paper	$	68,390	$	68,390
Corporate debt securities		74,535		74,535
Money market funds		1,829		1,829

	$	144,754	$	144,754

	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	269,722	$	269,722
Derivative liability		265		—		265
Deferred compensation plan liability		1,479		—		1,479

	$	1,744	$	269,722	$	271,466

	Level 2		Total
Commercial paper		25,724		25,724
Corporate debt securities		118,474		118,474
Certificate of deposit		350		350
Market exchanged mutual funds		658		658

	$	145,206	$	145,206

	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	274,077	$	274,077
Deferred compensation plan liability		667		—		667

	$	667	$	274,077	$	274,744

Schedule of changes in contingent consideration payable

The following table shows the change in the balance of contingent consideration payable for the year ended December 31, 2016 and 2015, respectively (in thousands):

	Year ended December 31,
	2016			2015
Balance, beginning of the period	$	274,077		$	10,700
Additions, from business acquisitions		—			259,000
Payment of contingent consideration in cash		(5,000	)		—
Payment of contingent consideration in stock		(6,115	)		—
Unrealized change in fair value change during the period, included in Statement of Operations		6,760			4,377

Balance, end of the period	$	269,722		$	274,077

Scioderm

Schedule of significant unobservable inputs used in the valuation of the contingent consideration payable

Contingent Consideration Liability	Fair value as of December 31, 2016	Valuation Technique	Unobservable Input	Range
			Discount rate	0.62% - 3.8%
Clinical and regulatory milestones	$237.2 million	Probability weighted discounted cash flow	Probability of achievement of milestones	66.5% - 100.0%
			Projected year of payments	2017-2019
			Revenue volatility	58%
			Probability of achievement of milestones	66.5%
Revenue-based milestones	$22.8 million	Monte Carlo	Discount rate	1.47% - 2.55%
			Projected year of payments	2019-2029

Callidus

Schedule of significant unobservable inputs used in the valuation of the contingent consideration payable

Contingent Consideration Liability	Fair value as of December 31, 2016	Valuation Technique	Unobservable Input	Range
			Discount rate	12.5%
Clinical and regulatory milestones	$9.3 million	Probability weighted discounted cash flow	Probability of achievement of milestones	30.4%-42.8%
			Projected year of payments	2018-2022

Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases

Schedule of current significant leased properties

The following table contains information about our current significant leased properties as of December 31, 2016:

Location	Approximate Square Feet		Use	Lease expiry date
Cranbury, New Jersey		90,000	Office and laboratory	September 2025
Durham, North Carolina		5,603	Office	June 2018
Buckinghamshire, United Kingdom		9,821	Office	September 2020
Munich, Germany		4,316	Office	April 2017

Schedule of aggregate annual future minimum lease payments under the operating leases

At December 31, 2016, aggregate annual future minimum lease payments under these leases are as follows:

(in thousands)		2017			2018			2019			2020			2021 and beyond			Total
Minimum lease payments		$	2,666		$	2,483		$	2,421		$	2,349		$	10,537		$	20,456

Schedule of aggregate annual future minimum lease payments under the capital leases, including interest

At December 31, 2016, aggregate annual future minimum lease payments under these leases, including interest, are as follows (in thousands):

Years ending December 31:
2017	$	355
2018		355
2019		134
2020		—
2021 and beyond		—

Total principal obligation	$	844

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Taxes

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,
	2016			2015			2014
United States	$	(174,913	)	$	(123,697	)	$	(70,030	)
Foreign		(28,868	)		(8,421	)		(9	)

Total	$	(203,781	)	$	(132,118	)	$	(70,039	)

Schedule of reconciliation of the statutory tax rates and the effective tax rates

	Years Ended December 31,
	2016			2015			2014
Statutory rate		(34	)%		(34	)%		(34	)%
State taxes, net of federal benefit		(5	)		(5	)		(4	)
Permanent adjustments		3			2			1
R&D credit		(3	)		(3	)		(4	)
Foreign income tax rate differential		2			1			—
Other		(1	)		2			1
Valuation allowance		36			37			38

Net		(2	)%		(0	)%		(2	)%

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,
	2016			2015
Non-current deferred tax assets
Intellectual property	$	95,956		$	—
Amortization/depreciation		1,781			2,657
Research tax credit		32,851			27,170
Net operating loss carry forwards		253,661			159,889
Deferred revenue		14,281			14,281
Non-cash stock issue		11,649			6,767
Others		3,358			2,964

Gross deferred tax assets		413,537			213,728
Deferred tax liability related to business acquisition		(173,771	)		(176,219	)
Deferred tax liability related to royalty payable		(96,829	)		—
Deferred tax liability related to convertible notes		(29,845	)		—

Total net deferred tax asset		113,092			37,509
Less valuation allowance		(286,863	)		(213,728	)

Net deferred tax assets (liability)	$	(173,771	)	$	(176,219	)

Debt Instruments and Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2016

Debt Instruments and Related Party Transactions

Schedule of liability components of the Convertible Notes

The Convertible Notes consist of the following as of December 31, 2016:

Liability component	(In thousands)
Principal	$	250,000
Less: debt discount (1)		(90,807	)
Less: deferred financing (1)		(4,729	)

Net carrying value of the debt	$	154,464


(1)	Included in the Consolidated Balance Sheets within Convertible Senior Notes (due 2023) and amortized to interest expense over the remaining life of the Convertible Senior Notes using the effective interest rate method.

Components of total interest expense recognized related to the Convertible Notes

The following table sets forth total interest expense recognized related to the Convertible Notes for the year ended December 31, 2016:

Components	(In thousands)
Contractual interest expense	$	208
Amortization of deferred financing		26
Amortization of debt discount		248
Total	$	482

Effective interest rate of the liability component		10.85	%

Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings per Share

Schedule of reconciliation of the numerator and denominator used in computing basic and diluted net loss per common share

	Years Ended December 31,
Historical	2016			2015			2014
Numerator:
Net loss attributable to common stockholders	$	(200,042	)	$	(132,118	)	$	(68,926	)


Denominator:
Weighted average common shares outstanding—basic and diluted		134,401,588			109,923,815			74,444,157

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,
	2016		2015		2014
Options to purchase common stock		15,528		11,729		10,021
Convertible debt		40,850		—		—
Outstanding warrants, convertible to common stock		3,110		1,350		1,600
Unvested restricted stock units		744		479		955

Total number of potentially issuable shares		60,232		13,558		12,576

Selected Quarterly Financial Data (Unaudited - in thousands except per share data) (Tables)

12 Months Ended

Dec. 31, 2016

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
2016
Net loss	$	(43,691	)	$	(51,050	)	$	(46,654	)	$	(58,647	)
Basic and diluted net loss per common share (1)		(0.35	)		(0.40	)		(0.33	)		(0.41	)
2015
Net loss	$	(24,288	)	$	(27,133	)	$	(37,800	)	$	(42,897	)
Basic and diluted net loss per common share (1)		(0.25	)		(0.27	)		(0.32	)		(0.34	)


(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 (Details) $ / shares in Units, $ in Thousands			1 Months Ended				3 Months Ended	4 Months Ended	12 Months Ended
	Dec. 21, 2016 USD ($)	Jul. 05, 2016 USD ($)	Feb. 29, 2016	Jun. 30, 2015 USD ($)	Nov. 30, 2014 USD ($) $ / shares	Jul. 31, 2014 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Jul. 31, 2016 USD ($) shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) shares	Apr. 01, 2016 item
Corporate Information, Status of Operations and Management Plans
Number of Fabry causing mutations included in the label approved by the CHMP \| item												313
Net product sales									$ 4,958
Common stock, par value (in dollars per share) \| $ / shares									$ 0.01	$ 0.01
Net proceeds from convertible notes to pay capped call transactions									$ 13,450
Common Stock, Par or Stated Value Per Share \| $ / shares									$ 0.01	$ 0.01
Net proceeds from stock issued at ATM transactions									$ 97,068		$ 38,636
Proceeds from the issuance of common stock (in dollars)									97,068	$ 243,042	$ 135,805
Accumulated deficit									$ (779,608)	$ (579,566)
Galafold \| EU
Corporate Information, Status of Operations and Management Plans
Net product sales							$ 5,000
Cowen and Company, LLC \| Sales Agreement
Corporate Information, Status of Operations and Management Plans
Number of shares issued from ATM transactions (in shares) \| shares								15,000,000
Net proceeds from stock issued at ATM transactions								$ 97,100
Commission expenses incurred on issue of common stock								2,700
Other expenses paid								$ 200
Common Stock
Corporate Information, Status of Operations and Management Plans
Common stock, par value (in dollars per share) \| $ / shares					$ 0.01
Common Stock, Par or Stated Value Per Share \| $ / shares					$ 0.01
Number of shares issued from ATM transactions (in shares) \| shares									14,989,027		14,328,224
Net proceeds from stock issued at ATM transactions									$ 150		$ 143
Proceeds from the issuance of common stock (in dollars)				$ 243,000	$ 97,200
Common Stock \| Cowen and Company, LLC \| At the market ("ATM") equity offering
Corporate Information, Status of Operations and Management Plans
Common stock, par value (in dollars per share) \| $ / shares						$ 0.01
Common Stock, Par or Stated Value Per Share \| $ / shares						$ 0.01
Number of shares issued from ATM transactions (in shares) \| shares						14,300,000
Proceeds from the issuance of common stock (in dollars)						$ 38,600
Convertible Notes \| 2016 Convertible Notes
Corporate Information, Status of Operations and Management Plans
Aggregate principle amount	$ 250,000
Fixed interest rate (as a percent)	3.00%
Proceeds from Debt, Net of Issuance Costs	$ 243,100
Net proceeds from convertible notes to pay capped call transactions	$ 13,500
Maximum
Corporate Information, Status of Operations and Management Plans
Percentage of patients with Fabry disease caused by mutations included in the label approved by the CHMP												0.5
Maximum \| Cowen and Company, LLC \| Sales Agreement
Corporate Information, Status of Operations and Management Plans
Fixed commission rate as a percentage of gross proceeds per Share sold			3.00%					3.00%
MiaMed Inc
Corporate Information, Status of Operations and Management Plans
Total consideration, stock and cash		$ 6,500
Contingent consideration payable upon achievement of milestones		83,000
Potential aggregate deal value		$ 89,500

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Minimum
Property and Equipment
Estimated useful lives	3 years
Maximum
Property and Equipment
Estimated useful lives	5 years

Summary of Significant Accounting Policies - Equity Incentive Plan and Stock-Based Compensation (Details)	Dec. 31, 2016 item
Stock-Based Compensation
Number of stock-based employee compensation plans	3

Summary of Significant Accounting Policies - Segment Information (Details)	12 Months Ended
	Dec. 31, 2016 segment
Summary of Significant Accounting Policies
Number of business segments	1

Acquisitions (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended	12 Months Ended
Acquisitions (Details) - USD ($) $ in Thousands	Jul. 05, 2016	Sep. 30, 2015	Apr. 30, 2016	Nov. 30, 2013	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquisitions
Contingent consideration payable						$ 269,722	$ 274,077
Contingent consideration payable, current portion						56,101	41,400
Changes in fair value of contingent consideration payable						6,760	4,377	$ 100
Payment of contingent consideration in stock, impact on stockholder's equity						6,115
Scioderm
Acquisitions
Initial amount to Effective Time Holders		$ 223,900
Initial amount cash payment excluding Series B Preferred		141,100
Initial amount paid in shares of Common Stock		$ 82,800
Priority review voucher transfer years		1 year
Payment to be made if Priority Review Voucher is obtained and used		$ 100,000
Contingent consideration payable		259,000				260,000
Contingent consideration payable, current portion						56,100
Scioderm \| Changes in fair value of contingent consideration payable
Acquisitions
Changes in fair value of contingent consideration payable						7,300
Scioderm \| IPR&D
Acquisitions
Intangible assets-IPR&D							$ 463,700
Scioderm \| Maximum
Acquisitions
Priority Review Voucher sale proceeds shared		$ 100,000
Priority Review Voucher sale proceeds shared (as a percent)		50.00%
Scioderm \| Scioderm \| Series B Preferred Stock
Acquisitions
Consideration paid in common stock		5,900,000
Callidus
Acquisitions
Contingent consideration payable				$ 10,600		9,700
Discount rate (as a percent)				13.50%
Milestone payment, value of shares issued					$ 6,000
Payment of contingent consideration in stock, impact on stockholder's equity					6,100
Callidus \| Changes in fair value of contingent consideration payable
Acquisitions
Changes in fair value of contingent consideration payable						(500)
MiaMed Inc
Acquisitions
Total consideration, stock and cash	$ 6,500
Cash consideration paid	1,800
Contingent consideration payable upon achievement of milestones	83,000
Potential aggregate deal value	89,500
Research and development expense	$ 6,500
MiaMed Inc \| Amicus \| Common Stock
Acquisitions
Consideration paid in common stock	825,603
Clinical, Regulatory and Commercial milestones \| MiaMed Inc \| Maximum
Acquisitions
Contingent consideration payable upon achievement of milestones	$ 83,000
Clinical and Regulatory Approval milestones \| Scioderm
Acquisitions
Contingent consideration payable						237,200
Milestone payment					$ 5,000
Clinical and Regulatory Approval milestones \| Scioderm \| Minimum
Acquisitions
Discount rate (as a percent)		0.40%
Clinical and Regulatory Approval milestones \| Scioderm \| Maximum
Acquisitions
Upfront cash payments		$ 361,000	$ 361,000
Discount rate (as a percent)		1.10%
Clinical and Regulatory Approval milestones \| Callidus
Acquisitions
Contingent consideration payable						9,300
Revenue-based milestones \| Scioderm
Acquisitions
Upfront equity payments		$ 257,000
Contingent consideration payable						22,800
Revenue-based milestones \| Scioderm \| Minimum
Acquisitions
Discount rate (as a percent)		1.00%
Revenue-based milestones \| Scioderm \| Maximum
Acquisitions
Upfront equity payments						$ 257,000
Discount rate (as a percent)		2.20%
Clinical milestone \| Scioderm \| Maximum
Acquisitions
Upfront cash payments			81,000
Regulatory Approval milestone \| Scioderm \| Maximum
Acquisitions
Upfront cash payments			$ 280,000

Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Changes in goodwill
Balance at beginning of the period	$ 197,797
Balance at end of the period	197,797
Business Acquisitions
Changes in goodwill
Balance at beginning of the period	197,800
Balance at end of the period	197,800
Goodwill impairment loss	$ 0

Goodwill and Intangible Assets - IPR&D (Details) - Business Acquisitions $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Changes in IPR&D
Balance at beginning of the period	$ 486.7
Balance at end of the period	486.7
Impairment of IPR&D	$ 0.0

Cash, Money Market Funds and Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash, Money Market Funds, and Marketable Securities
Cash and cash equivalents, Amortized Cost		$ 187,026	$ 69,485	$ 24,074	$ 43,640
Cash and cash equivalents, Fair Value		187,026	69,485
Marketable securities, Fair Value current portion		143,325	144,548
Marketable securities, Amortized Cost		143,222	144,663
Unrealized Gain		134	39
Unrealized Loss		(31)	(154)
Marketable securities, Fair Value		143,325	144,548
Cash and marketable securities, Amortized Cost		330,248	214,148
Cash and marketable securities, Fair Value		330,351	214,033
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		58,700	118,500
Other current liabilities
Cash, Money Market Funds, and Marketable Securities
Derivative liabilities	$ 300	265
Other expense
Cash, Money Market Funds, and Marketable Securities
Gain (loss) on derivative instruments	$ (300)
Short term corporate debt securities
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized cost current portion		74,564	118,627
Unrealized Gain current portion		2	1
Unrealized Loss current portion		(31)	(154)
Marketable securities, Fair Value current portion		74,535	118,474
Commercial paper
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost		68,258	25,686
Unrealized Gain		132	38
Marketable securities, Fair Value		68,390	25,724
Money market
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost		350
Marketable securities, Fair Value		350
Certificate of deposit
Cash, Money Market Funds, and Marketable Securities
Marketable securities, Amortized Cost		50	350
Marketable securities, Fair Value		$ 50	$ 350

Inventories (Details) - USD ($) $ in Thousands	12 Months Ended
Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventories
Work-in-process	$ 3,308
Finished goods	108
Total inventories	3,416	$ 0
Inventory write-downs	$ 0

Property and Equipment (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Property and equipment, gross	$ 22,311,000	$ 19,531,000
Less accumulated depreciation	(12,495,000)	(13,353,000)
Property and equipment, net	9,816,000	6,178,000
Depreciation expense for capital lease obligation	200,000
Capital lease obligations outstanding		0
Computer equipment
Property and Equipment
Property and equipment, gross	3,511,000	5,075,000
Computer software
Property and Equipment
Property and equipment, gross	1,347,000	1,354,000
Research equipment
Property and Equipment
Property and equipment, gross	7,465,000	6,483,000
Furniture and fixtures
Property and Equipment
Property and equipment, gross	3,018,000	2,444,000
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 6,970,000	$ 4,175,000

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued expenses
Accounts payable	$ 12,905	$ 16,477
Accrued professional fees	5,079	3,578
Accrued contract manufacturing & contract research costs	8,042	2,940
Accrued compensation and benefits	9,981	6,201
Accrued facility costs	1,740	1,321
Foreign currency forward contract	265
Capital lease, short term portion	283
Accrued other	2,713	1,699
Accounts payable and accrued expenses	$ 41,008	$ 32,216

Stockholders' Equity - Common Stock and Warrants (Details) $ / shares in Units, $ in Thousands				1 Months Ended					4 Months Ended	12 Months Ended
	Dec. 21, 2016 USD ($) $ / shares	Jul. 05, 2016 USD ($) shares	Sep. 30, 2015 USD ($)	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($) shares	Jun. 30, 2015 USD ($) $ / shares shares	Nov. 30, 2014 USD ($) $ / shares shares	Jul. 31, 2014 USD ($) $ / shares shares	Jul. 31, 2016 USD ($) shares	Dec. 31, 2016 USD ($) item $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) shares	Jun. 30, 2016 USD ($) $ / shares shares	Oct. 31, 2015 USD ($) shares
Convertible Debt
Common stock, par value (in dollars per share) \| $ / shares										$ 0.01	$ 0.01
Authorized number of shares of common stock \| shares										250,000,000	250,000,000
Voting right for each share held, number \| item										1
Common stock, par value (in dollars per share) \| $ / shares										$ 0.01	$ 0.01
Net proceeds from stock issued at ATM transactions										$ 97,068		$ 38,636
Warrant liability										16,076	$ 8,755
Net proceeds from the issuance of common stock										$ 97,068	$ 243,042	$ 135,805
Common Stock
Convertible Debt
Common stock, par value (in dollars per share) \| $ / shares							$ 0.01
Common stock, par value (in dollars per share) \| $ / shares							$ 0.01
Number of shares issued from ATM transactions (in shares) \| shares										14,989,027		14,328,224
Net proceeds from stock issued at ATM transactions										$ 150		$ 143
Stock issued from public offering / financing (in shares) \| shares						19,500,000	15,900,000				19,528,302	15,927,500
Public offering share price (in dollars per share) \| $ / shares						$ 13.25	$ 6.50
Net proceeds from the issuance of common stock						$ 243,000	$ 97,200
Cowen and Company, LLC \| Sales Agreement
Convertible Debt
Number of shares issued from ATM transactions (in shares) \| shares									15,000,000
Net proceeds from stock issued at ATM transactions									$ 97,100
Commission expenses incurred on issue of common stock									2,700
Other Expenses									$ 200
Cowen and Company, LLC \| Sales Agreement \| Maximum
Convertible Debt
Fixed commission rate as a percentage of gross proceeds per Share sold					3.00%				3.00%
Cowen and Company, LLC \| At the market ("ATM") equity offering \| Common Stock
Convertible Debt
Common stock, par value (in dollars per share) \| $ / shares								$ 0.01
Common stock, par value (in dollars per share) \| $ / shares								$ 0.01
Number of shares issued from ATM transactions (in shares) \| shares								14,300,000
Net proceeds from the issuance of common stock								$ 38,600
Aggregate offering proceeds from issuance of common stock								$ 40,000
Scioderm
Convertible Debt
Initial amount to Effective Time Holders			$ 223,900
Initial amount cash payment excluding Series B Preferred			141,100
Initial amount paid in shares of Common Stock			82,800
Scioderm \| Revenue-based milestones
Convertible Debt
Upfront equity payments			257,000
Scioderm \| Maximum \| Clinical and Regulatory Approval milestones
Convertible Debt
Upfront cash payments			$ 361,000	$ 361,000
Scioderm \| Maximum \| Revenue-based milestones
Convertible Debt
Upfront equity payments										$ 257,000
MiaMed Inc
Convertible Debt
Total consideration, stock and cash		$ 6,500
Cash consideration paid		1,800
Contingent consideration payable upon achievement of milestones		83,000
Potential aggregate deal value		$ 89,500
MiaMed Inc \| Amicus \| Common Stock
Convertible Debt
Consideration paid in common stock \| shares		825,603
October 2015 Purchase Agreement \| Redmile Group
Convertible Debt
Fixed interest rate (as a percent)														4.10%
Warrant liability														$ 8,800
October 2015 Purchase Agreement \| Redmile Group \| Private Placement Purchase Agreement
Convertible Debt
Aggregate principle amount														$ 50,000
October 2015 Purchase Agreement \| Redmile Group \| Private Placement Purchase Agreement \| Warrants
Convertible Debt
Shares issuable for warrants (in shares) \| shares														1,300,000
February 2016 Purchase Agreement \| Redmile Group \| Private Placement Purchase Agreement \| Maximum
Convertible Debt
Shares issuable for warrants (in shares) \| shares					1,850,000
February 2016 Purchase Agreement \| Beneficial Owner \| Redmile Group \| Maximum
Convertible Debt
Aggregate principle amount					$ 75,000
February 2016 Purchase Agreement \| Beneficial Owner \| Redmile Group \| Private Placement Purchase Agreement
Convertible Debt
Aggregate principle amount					$ 50,000
Fixed interest rate (as a percent)					3.875%
February 2016 Purchase Agreement \| Beneficial Owner \| Redmile Group \| Private Placement Purchase Agreement \| Warrants
Convertible Debt
Shares issuable for warrants (in shares) \| shares					1,800,000
2016 Convertible Notes \| Convertible Notes
Convertible Debt
Aggregate principle amount	$ 250,000
Fixed interest rate (as a percent)	3.00%
Debt conversion ratio (in shares)	0.1633987
Conversion price (in dollars per share) \| $ / shares	$ 6.12
Additional Note and Warrant Agreement June 2016 \| Beneficial Owner \| Redmile Group \| Private Placement Purchase Agreement
Convertible Debt
Aggregate principle amount													$ 30,000
Fixed interest rate (as a percent)													3.875%
Common stock, par value (in dollars per share) \| $ / shares													$ 0.01
Common stock, par value (in dollars per share) \| $ / shares													$ 0.01
Additional Note and Warrant Agreement June 2016 \| Beneficial Owner \| Redmile Group \| Private Placement Purchase Agreement \| Warrants
Convertible Debt
Shares issuable for warrants (in shares) \| shares													1,300,000
Additional Note and Warrant Agreement June 2016 \| Beneficial Owner \| Redmile Group \| Private Placement Purchase Agreement \| Maximum \| Warrants
Convertible Debt
Shares issuable for warrants (in shares) \| shares													1,260,000

Stockholders' Equity - Equity Incentive Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders' Equity
Deferred compensation liability, noncurrent	$ 1,500,000	$ 700,000
Trading securities	1,500,000	700,000
Income from deferred compensation investments	34,000	17,000
Unrealized gain/(loss)	$ 32,000	$ 50,000
Fair value weighted-average assumptions:
Minimum stock price volatility (as a percent)	75.00%
Common stock options
Fair value weighted-average assumptions:
Maximum term of option	10 years
Expected stock price volatility (as a percent)	81.30%	75.90%	81.30%
Risk free interest rate (as a percent)	1.50%	1.70%	1.90%
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)	$ 0.00	$ 0.00	$ 0.00
Granted (in dollars per share)	$ 5.28	$ 7.51	$ 2.12
Number of Shares
Balance at the beginning of the period (in shares)	11,729,200	10,020,700	9,041,100
Options granted (in shares)	5,114,100	3,917,200	2,993,100
Options exercised (in shares)	(723,100)	(2,070,300)	(965,600)
Options forfeited (in shares)	(622,700)	(138,400)	(1,047,900)
Balance at the end of the period (in shares)	15,497,500	11,729,200	10,020,700
Vested and unvested expected to vest as of the end of the period (in shares)	14,593,700
Exercisable at the end of the period (in shares)	7,545,300
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 7.11	$ 5.02	$ 5.65
Options granted (in dollars per share)	7.67	11.61	2.99
Options exercised (in dollars per share)	4.20	5.43	3.80
Options forfeited (in dollars per share)	8.62	7.76	5.76
Balance at the end of the period (in dollars per share)	7.37	$ 7.11	$ 5.02
Vested and unvested expected to vest as of the end of the period (in dollars per share)	7.31
Exercisable at the end of the period (in dollars per share)	$ 6.57
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 9 months 18 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding (in dollars)	$ 7,800
Aggregate intrinsic value of options vested and unvested expected to vest (in dollars)	7,700
Aggregate intrinsic value of options exercisable (in dollars)	5,800
Aggregate intrinsic value of options exercised (in dollars)	2,600,000	$ 14,700,000	$ 2,800,000
Cash proceeds from stock options exercised (in dollars)	3,000,000	$ 11,200,000	$ 3,700,000
Total unrecognized compensation cost related to non-vested stock options granted (in dollars)	$ 33,700,000
Period of recognition unrecognized compensation costs (in years)	2 years 9 months 18 days
Common stock options \| 2002 Plan and 2007 Plan
Fair value weighted-average assumptions:
Percentage of options vest on the first year 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%
Restricted stock units (RSUs)
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
Restricted Stock Units, Number of Shares
Non-vested units as of the beginning of the period (in shares)	478,500
Granted (in shares)	582,700	366,000
Vested (in shares)	(281,900)	(842,500)
Forfeited (in shares)	(34,900)
Non-vested units as of the end of the period (in shares)	744,400	478,500
Weighted Average Grant Date Fair Value
Non-vested units as of the beginning of the period (in dollars per share)	$ 10.38
Granted (in dollars per share)	6.21	$ 12.63
Vested (in dollars per share)	8.73
Forfeited (in dollars per share)	7.71
Non-vested units as of the end of the period (in dollars per share)	$ 7.86	$ 10.38
Weighted Average Remaining Years
Non-vested units as of the end of the period	2 years 7 months 13 days
Restricted stock units (RSUs) \| Performance-Based RSU Agreement
Weighted Average Remaining Years
Units issued under the Plan	0
Restricted stock
Aggregate Intrinsic Value
Total unrecognized compensation cost related to non-vested stock options granted (in dollars)	$ 4,200,000
Period of recognition unrecognized compensation costs (in years)	2 years 7 months 13 days
Maximum \| Common stock options \| 2007 Plan and 2007 Director Plan
Fair value weighted-average assumptions:
Number of shares reserved for issuance	12,630,551

Stockholders' Equity - Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity compensation expense
Total equity compensation expense	$ 17,504	$ 9,972	$ 6,008
Research and development expense
Equity compensation expense
Total equity compensation expense	8,071	4,600	2,703
Selling, general and administrative expenses
Equity compensation expense
Total equity compensation expense	$ 9,433	$ 5,372	$ 3,305

Assets and Liabilities Measured at Fair Value (Details) $ in Thousands			1 Months Ended	12 Months Ended
	Jul. 05, 2016 USD ($)	Sep. 30, 2015 USD ($)	Nov. 30, 2013 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Oct. 31, 2015 USD ($)
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
Assets:
Fair value of assets				144,754	$ 145,206
Trading securities				1,500	700
Liabilities:
Contingent consideration payable				269,722	274,077
Derivative liability				265
Deferred compensation plan liability				1,479	667
Fair value of liabilities				271,466	274,744
Contingent consideration payable				269,722	274,077
Contingent consideration payable
Balance, beginning of the period				274,077	10,700
Additions, from business acquisitions					259,000
Payment of contingent consideration in cash				(5,000)
Payment of contingent consideration in stock				(6,115)
Unrealized change in fair value change during the period, included in Statement of Operations				6,760	4,377	$ 100
Balance, end of the period				269,722	$ 274,077	$ 10,700
Foreign Currency Exchange Rate Exposure
Number Of Forward Contracts \| item					0
Non-cash changes in the fair value of derivative liability				(265)
Other current liabilities
Foreign Currency Exchange Rate Exposure
Derivative liabilities				265			$ 300
Callidus
Liabilities:
Contingent consideration payable			$ 10,600	9,700
Contingent consideration payable			$ 10,600	9,700
Discount rate (as a percent)			13.50%
Scioderm
Liabilities:
Contingent consideration payable		$ 259,000		260,000
Contingent consideration payable		$ 259,000		260,000
MiaMed Inc
Liabilities:
Contingent consideration payable upon achievement of milestones	$ 83,000
Potential aggregate deal value	89,500
Clinical and Regulatory Approval milestones \| Callidus
Liabilities:
Contingent consideration payable				9,300
Contingent consideration payable				9,300
Clinical and Regulatory Approval milestones \| Scioderm
Liabilities:
Contingent consideration payable				237,200
Contingent consideration payable				237,200
Revenue-based milestones \| Scioderm
Liabilities:
Contingent consideration payable				22,800
Contingent consideration payable				22,800
Minimum \| Clinical and Regulatory Approval milestones \| Scioderm
Liabilities:
Discount rate (as a percent)		0.40%
Minimum \| Revenue-based milestones \| Scioderm
Liabilities:
Discount rate (as a percent)		1.00%
Maximum \| Clinical and Regulatory Approval milestones \| Scioderm
Liabilities:
Discount rate (as a percent)		1.10%
Maximum \| Revenue-based milestones \| Scioderm
Liabilities:
Discount rate (as a percent)		2.20%
Maximum \| Clinical, Regulatory and Commercial milestones \| MiaMed Inc
Liabilities:
Contingent consideration payable upon achievement of milestones	$ 83,000
Commercial paper
Assets:
Fair value of assets				68,390	$ 25,724
Corporate debt securities
Assets:
Fair value of assets				74,535	118,474
Certificate of deposit
Assets:
Fair value of assets					350
Market exchanged mutual funds
Assets:
Fair value of assets				1,829	658
Level 2
Assets:
Fair value of assets				144,754	145,206
Liabilities:
Derivative liability				265
Deferred compensation plan liability				1,479	667
Fair value of liabilities				1,744	667
Level 2 \| Commercial paper
Assets:
Fair value of assets				68,390	25,724
Level 2 \| Corporate debt securities
Assets:
Fair value of assets				74,535	118,474
Level 2 \| Certificate of deposit
Assets:
Fair value of assets					350
Level 2 \| Market exchanged mutual funds
Assets:
Fair value of assets				1,829	658
Level 3
Liabilities:
Contingent consideration payable				269,722	274,077
Fair value of liabilities				269,722	274,077
Contingent consideration payable				$ 269,722	$ 274,077
Level 3 \| Clinical and Regulatory Approval milestones \| Probability weighted discounted cash flow \| Callidus
Liabilities:
Discount rate (as a percent)				12.50%
Level 3 \| Revenue-based milestones \| Monte Carlo \| Scioderm
Liabilities:
Probability of achievement of milestones (as a percent)				66.50%
Revenue volatility (as a percent)				58.00%
Level 3 \| Minimum \| Clinical and Regulatory Approval milestones \| Probability weighted discounted cash flow \| Callidus
Liabilities:
Probability of achievement of milestones (as a percent)				30.40%
Level 3 \| Minimum \| Clinical and Regulatory Approval milestones \| Probability weighted discounted cash flow \| Scioderm
Liabilities:
Discount rate (as a percent)				0.62%
Probability of achievement of milestones (as a percent)				66.50%
Level 3 \| Minimum \| Revenue-based milestones \| Monte Carlo \| Scioderm
Liabilities:
Discount rate (as a percent)				1.47%
Level 3 \| Maximum \| Clinical and Regulatory Approval milestones \| Probability weighted discounted cash flow \| Callidus
Liabilities:
Probability of achievement of milestones (as a percent)				42.80%
Level 3 \| Maximum \| Clinical and Regulatory Approval milestones \| Probability weighted discounted cash flow \| Scioderm
Liabilities:
Discount rate (as a percent)				3.80%
Probability of achievement of milestones (as a percent)				100.00%
Level 3 \| Maximum \| Revenue-based milestones \| Monte Carlo \| Scioderm
Liabilities:
Discount rate (as a percent)				2.55%
Redmile Group \| October 2015 Purchase Agreement \| Private Placement Purchase Agreement
Financial assets and liabilities subject to fair value measurements
Proceeds from note and warrant purchase agreement									$ 50,000
Redmile Group \| Additional Note and Warrant Agreement June 2016 \| Beneficial Owner \| Private Placement Purchase Agreement
Financial assets and liabilities subject to fair value measurements
Proceeds from note and warrant purchase agreement								$ 30,000

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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)	$ 1.2	$ 0.9	$ 0.6

Leases (Details)	12 Months Ended
Leases (Details)	Dec. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Minimum lease payments
2017	$ 2,666,000
2018	2,483,000
2019	2,421,000
2020	2,349,000
2021 and beyond	10,537,000
Total	20,456,000
Rent expense, including fees for utilities and common area maintenances	3,500,000	$ 2,600,000	$ 2,400,000
Capital Leases
Capital lease obligation		$ 0
Equipment
Capital Leases
Capital lease obligation	$ 900,000
Capital leases, interest rate, minimum	0.20%
Capital leases, interest rate, maximum	5.70%
2017	$ 355,000
2018	355,000
2019	134,000
Total principle obligation	$ 844,000
Equipment \| Minimum
Capital Leases
Term of capital lease (in months)	36 months
Equipment \| Maximum
Capital Leases
Term of capital lease (in months)	48 months
Cranbury, New Jersey \| Office and laboratory space
Operating Leases
Area of space leased (in square feet) \| ft²	90,000
Durham, North Carolina \| Office space
Operating Leases
Area of space leased (in square feet) \| ft²	5,603
Buckinghamshire, United Kingdom \| Office space
Operating Leases
Area of space leased (in square feet) \| ft²	9,821
Munich, Germany \| Office space
Operating Leases
Area of space leased (in square feet) \| ft²	4,316

Income Taxes - Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income (loss) before income taxes:
United States	$ (174,913)	$ (123,697)	$ (70,030)
Foreign	(28,868)	(8,421)	(9)
Loss before income tax benefit	$ (203,781)	$ (132,118)	$ (70,039)
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%)	(5.00%)	(4.00%)
Permanent adjustments (as a percent)	3.00%	2.00%	1.00%
R&D credit (as a percent)	(3.00%)	(3.00%)	(4.00%)
Foreign income tax rate differential (as a percent)	2.00%	1.00%
Other (as a percent)	(1.00%)	2.00%	1.00%
Valuation allowance (as a percent)	36.00%	37.00%	38.00%
Net (as a percent)	(2.00%)	(0.00%)	(2.00%)
Income tax benefit from the sale of net operating losses and research and development credits	$ 0	$ 0	$ 1,100
Income tax benefit	(3,739)		$ (1,113)
Reduction in valuation allowance related to income tax associated with gain on foreign currency translation	1,200
Income tax benefit in connection with the reduction in North Carolina state tax rates	$ 2,700

Income Taxes - Deferred and Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Recognized interest and penalties		$ 0
Accrual for interest and penalties		0
Accrual for uncertain tax positions		0
Non-current deferred tax assets
Intellectual property	$ 95,956
Amortization/depreciation	1,781	2,657
Research tax credit	32,851	27,170
Net operating loss carry forwards	253,661	159,889
Deferred revenue	14,281	14,281
Non-cash stock issue	11,649	6,767
Others	3,358	2,964
Gross deferred tax assets	413,537	213,728
Deferred tax liability related to business acquisition	(173,771)	(176,219)
Deferred tax liability related to royalty payable	(96,829)
Deferred tax liability related to convertible notes	(29,845)
Total net deferred tax asset	113,092	37,509
Less valuation allowance	(286,863)	(213,728)
Net deferred tax assets (liability)	(173,771)	(176,219)
Increase in the valuation allowance	$ 73,200	$ 65,300

Income Taxes - Loss Carryforwards (Details) $ in Millions	12 Months Ended
Income Taxes - Loss Carryforwards (Details) $ in Millions	Dec. 31, 2016 USD ($)
Net operating loss carry forwards
Period for measuring the change in ownership	3 years
Maximum change in ownership percentage allowed before statutory limitations imposed on the availability of net operating losses	50.00%
Tax benefit associated with exercise of stock options to be recorded in additional paid-in capital on recognition of associated NOL	$ 4.6
Federal
Net operating loss carry forwards
Amount of net operating loss carry forwards	637.0
Writedown of NOL's and R&D credits subject to Section 382 limitation	0.0
Foreign
Net operating loss carry forwards
Amount of net operating loss carry forwards	40.0
State
Net operating loss carry forwards
Amount of net operating loss carry forwards	$ 623.0

Licenses (Details) - License agreement - MSSM	12 Months Ended
Licenses (Details) - License agreement - MSSM	Dec. 31, 2016 USD ($)
Licenses
Upfront and annual license fees paid	$ 0
Potential milestone payments	0
Royalty expense	$ 100,000

Collaborative Agreements (Details) $ in Thousands	1 Months Ended	6 Months Ended	12 Months Ended
Collaborative Agreements (Details) $ in Thousands	Nov. 30, 2013 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Collaborative Agreements
Research revenue for work performed under cost sharing arrangement			$ 1,224
GSK \| Revised Agreement
Collaborative Agreements
Upfront payment received	$ 0
Potential milestone payments upon achievement of post-approval and sales-based milestones	$ 40,000
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
Milestone revenue recognized		$ 500
Biogen Idec
Collaborative Agreements
Research revenue for work performed under cost sharing arrangement			$ 1,200

Debt Instruments and Related Party Transactions - Note and Warrant Purchase Agreements (Details)	1 Months Ended			12 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares	Feb. 29, 2016 USD ($) item shares	Oct. 31, 2015 USD ($) installment shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares
Debt Instruments and Related Party Transactions [Line Items]
Common stock, par value (in dollars per share) \| $ / shares				$ 0.01	$ 0.01
Warrants				$ 16,076,000	$ 8,755,000
Loss on extinguishment of debt				13,302,000	$ 952,000
Redmile Group \| October 2015 Purchase Agreement
Debt Instruments and Related Party Transactions [Line Items]
Number of installments for repayment of debt \| installment			2
Fixed interest rate (as a percent)			4.10%
Warrants			$ 8,800,000
Redmile Group \| October 2015 Purchase Agreement \| Private Placement Purchase Agreement
Debt Instruments and Related Party Transactions [Line Items]
Ownership position in the company (as a percent)			6.70%
Proceeds from note and warrant purchase agreement			$ 50,000,000
Redmile Group \| October 2015 Purchase Agreement \| Private Placement Purchase Agreement \| Warrants
Debt Instruments and Related Party Transactions [Line Items]
Warrant Term			5 years
Shares issuable for warrants (in shares) \| shares			1,300,000
Redmile Group \| February 2016 Purchase Agreement \| Beneficial Owner \| Maximum
Debt Instruments and Related Party Transactions [Line Items]
Proceeds from note and warrant purchase agreement		$ 75,000,000
Redmile Group \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Maximum
Debt Instruments and Related Party Transactions [Line Items]
Shares issuable for warrants (in shares) \| shares		1,850,000
Redmile Group \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Warrants \| Maximum
Debt Instruments and Related Party Transactions [Line Items]
Shares of common stock issued per increment of note principal \| shares		37
Redmile Group \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Beneficial Owner
Debt Instruments and Related Party Transactions [Line Items]
Proceeds from note and warrant purchase agreement		$ 50,000,000
Number of installments for repayment of debt \| item		2
Fixed interest rate (as a percent)		3.875%
Redmile Group \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Beneficial Owner \| Warrants
Debt Instruments and Related Party Transactions [Line Items]
Warrant Term		5 years
Shares issuable for warrants (in shares) \| shares		1,800,000
Increment used for debt conversion		$ 1,000
Incremental fair value of warrant liability		3,500,000
Redmile Group \| Additional Note and Warrant Agreement June 2016 \| Private Placement Purchase Agreement \| Beneficial Owner
Debt Instruments and Related Party Transactions [Line Items]
Proceeds from note and warrant purchase agreement	$ 30,000,000
Fixed interest rate (as a percent)	3.875%
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01
Redmile Group \| Additional Note and Warrant Agreement June 2016 \| Private Placement Purchase Agreement \| Beneficial Owner \| Warrants
Debt Instruments and Related Party Transactions [Line Items]
Warrant Term	5 years
Shares issuable for warrants (in shares) \| shares	1,300,000
Increment used for debt conversion	$ 1,000
Redmile Group \| Additional Note and Warrant Agreement June 2016 \| Private Placement Purchase Agreement \| Beneficial Owner \| Warrants \| Maximum
Debt Instruments and Related Party Transactions [Line Items]
Shares issuable for warrants (in shares) \| shares	1,260,000
Shares of common stock issued per increment of note principal \| shares	42
Redmile Group \| December Note Purchase Agreement
Debt Instruments and Related Party Transactions [Line Items]
Loss on extinguishment of debt				$ 13,300,000
Redmile Group \| October 2017 payment \| October 2015 Purchase Agreement
Debt Instruments and Related Party Transactions [Line Items]
Installment payment			$ 15,000,000
Redmile Group \| October 2017 payment \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Beneficial Owner
Debt Instruments and Related Party Transactions [Line Items]
Installment payment		15,000,000
Redmile Group \| October 2020 payment \| October 2015 Purchase Agreement
Debt Instruments and Related Party Transactions [Line Items]
Installment payment			$ 35,000,000
Redmile Group \| October 2021 payment \| February 2016 Purchase Agreement \| Private Placement Purchase Agreement \| Beneficial Owner
Debt Instruments and Related Party Transactions [Line Items]
Installment payment		$ 35,000,000

Debt Instruments and Related Party Transactions - Convertible Debt (Details)			12 Months Ended
	Dec. 21, 2016 USD ($) $ / shares shares	Dec. 15, 2016 $ / item	Dec. 31, 2016 USD ($)
Convertible Debt
Net proceeds from convertible notes to pay capped call transactions			$ 13,450,000
Equity component of the Convertible Notes			88,346,000
Deferred tax liability in relation to the Convertible Notes			29,845,000
Convertible notes issuance costs			2,709,000
Interest Expense, Debt [Abstract]
Contractual interest expense			208,000
Amortization of deferred financing costs			26,000
Amortization of debt discount			248,000
Total interest expense			$ 482,000
Effective interest rate of the liability component			10.85%
Convertible Notes \| 2016 Convertible Notes
Convertible Debt
Aggregate principle amount	$ 250,000,000
Net proceeds after deducting fees and estimated expenses	243,100,000
Net proceeds from convertible notes to pay capped call transactions	$ 13,500,000
Shares of common stock issued per increment of note principal \| shares	40,849,675
Debt conversion ratio (in shares)	0.1633987
Increment used for debt conversion	$ 1,000
Conversion price (in dollars per share) \| $ / shares	$ 6.12
Maximum calendar days allowed to holders of common stock rights options or warrants to purchase of common stock	60 days
Trading days for price per share based on last reported sale price	10 days
Minimum percentage of per share value of last reported sale price of common stock	10.00%
Debt instrument term	7 years
Equity component of the Convertible Notes	$ 88,300,000
Convertible notes issuance costs	7,500,000
Convertible notes issuance cost paid	$ 6,900,000
Liability components of convertible notes
Principle			$ 250,000,000
Less: debt discount			(90,807,000)
Less: deferred financing			(4,729,000)
Net carrying value of debt			154,464,000
Fair value of the debt			$ 258,800,000
Interest Expense, Debt [Abstract]
Initial cap price \| $ / item		7.20
Capped call premium on closing price		50.00%
Convertible Notes \| 2016 Convertible Notes \| Convertible Notes, condition 1
Convertible Debt
Threshold consecutive trading days	30 days
Threshold percentage	130.00%
Convertible Notes \| 2016 Convertible Notes \| Convertible Notes, condition 1 \| Minimum
Convertible Debt
Threshold trading days	20 days
Convertible Notes \| 2016 Convertible Notes \| Convertible Notes, condition 2
Convertible Debt
Threshold trading days	5 days
Threshold consecutive trading days	5 days
Maximum threshold percentage	98.00%
Over-allotment Option \| Private Placement Purchase Agreement \| Convertible Notes \| 2016 Convertible Notes
Convertible Debt
Aggregate principle amount	$ 25,000,000

Earnings per Share (Details) - USD ($) $ in Thousands	12 Months Ended
Earnings per Share (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net loss attributable to common stockholders	$ (200,042)	$ (132,118)	$ (68,926)
Denominator:
Weighted average common shares outstanding - basic and diluted	134,401,588	109,923,815	74,444,157
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	60,232,000	13,558,000	12,576,000
Common stock options
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	15,528,000	11,729,000	10,021,000
Convertible debt
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	40,850,000
Warrants
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	3,110,000	1,350,000	1,600,000
Restricted stock units (RSUs)
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)	744,000	479,000	955,000

Commitments and Contingencies (Details)	Dec. 31, 2016 lawsuit
Commitments and Contingencies
Number of purported securities class action lawsuits	3
Number of purported securities class action lawsuits naming additional company officers as defendants	1

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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Data
Net loss	$ (58,647)	$ (46,654)	$ (51,050)	$ (43,691)	$ (42,897)	$ (37,800)	$ (27,133)	$ (24,288)	$ (200,042)	$ (132,118)	$ (68,926)
Basic and diluted net loss per common share (in dollars per share)	$ (0.41)	$ (0.33)	$ (0.40)	$ (0.35)	$ (0.34)	$ (0.32)	$ (0.27)	$ (0.25)	$ (1.49)	$ (1.20)	$ (0.93)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details