View Filing Data

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Jul. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	AMICUS THERAPEUTICS INC
Entity Central Index Key	0001178879
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		189,134,863
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 73,311	$ 49,060
Investments in marketable securities	465,641	309,502
Accounts receivable	15,077	9,464
Inventories	7,769	4,623
Prepaid expenses and other current assets	14,432	19,316
Total current assets	576,230	391,965
Investments in marketable securities	13,836	0
Property and equipment, less accumulated depreciation of $14,415 and $12,515 at June 30, 2018 and December 31, 2017, respectively	9,111	9,062
In-process research & development	23,000	23,000
Goodwill	197,797	197,797
Other non-current assets	5,915	5,200
Total Assets	825,889	627,024
Current liabilities:
Accounts payable, accrued expenses, and other current liabilities	41,613	53,890
Deferred reimbursements	2,750	7,750
Contingent consideration payable	8,600	8,400
Total current liabilities	52,963	70,040
Deferred reimbursements	14,156	14,156
Convertible notes	169,440	164,167
Contingent consideration payable	18,200	17,000
Deferred income taxes	6,465	6,465
Other non-current liability	2,770	2,346
Total liabilities	263,994	274,174
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value, 500,000,000 and 250,000,000 shares authorized, 189,053,214 and 166,989,790 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	1,939	1,721
Additional paid-in capital	1,723,865	1,400,758
Accumulated other comprehensive loss:
Foreign currency translation adjustment	(1,539)	(1,659)
Unrealized gain on available-for-sale securities	(455)	(436)
Warrants	13,063	16,076
Accumulated deficit	(1,174,978)	(1,063,610)
Total stockholders’ equity	561,895	352,850
Total Liabilities and Stockholders’ Equity	$ 825,889	$ 627,024

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accumulated depreciation of property and equipment (in dollars)	$ 14,415	$ 12,515
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	250,000,000
Common stock, shares issued	189,053,214	166,989,790
Common stock, shares outstanding	189,053,214	166,989,790

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Net product sales	$ 21,309	$ 7,158	$ 38,005	$ 11,327
Cost of goods sold	3,135	1,061	5,750	1,836
Gross Profit	18,174	6,097	32,255	9,491
Operating Expenses:
Research and development	34,660	31,985	75,458	62,861
Selling, general and administrative	29,172	19,311	56,568	38,443
Changes in fair value of contingent consideration payable	300	1,050	1,400	5,628
Depreciation	973	812	1,942	1,636
Total operating expenses	65,105	53,158	135,368	108,568
Loss from operations	(46,931)	(47,061)	(103,113)	(99,077)
Other income (expense):
Interest income	2,913	753	4,650	1,512
Interest expense	(4,560)	(4,179)	(9,048)	(8,469)
Change in fair value of derivatives	(7,600)	0	(2,739)	0
Other (expense) income	(5,316)	2,400	(2,554)	3,010
Loss before income tax	(61,494)	(48,087)	(112,804)	(103,024)
Income tax benefit (expense)	(339)	(49)	1,053	(105)
Net loss attributable to common stockholders	$ (61,833)	$ (48,136)	$ (111,751)	$ (103,129)
Net loss attributable to common stockholders per common share - basic and diluted (in dollars per share)	$ (0.33)	$ (0.34)	$ (0.61)	$ (0.72)
Weighted-average common shares outstanding - basic and diluted (in shares)	188,621,423	143,000,718	182,303,128	142,886,614

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (61,833)	$ (48,136)	$ (111,751)	$ (103,129)
Other comprehensive (loss) gain:
Foreign currency translation adjustment gain (loss), net of tax impact of $(109), $0, $(109), $0, respectively	2,308	(1,678)	503	(2,136)
Unrealized gain (loss) on available-for-sale securities	422	(155)	(19)	(72)
Other comprehensive income (loss)	2,730	(1,833)	484	(2,208)
Comprehensive loss	$ (59,103)	$ (49,969)	$ (111,267)	$ (105,337)

- 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) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustment gain (loss), tax (expense) benefit	$ (109)	$ 0	$ (109)	$ 0

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net loss	$ (111,751)	$ (103,129)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of debt discount and deferred financing	5,273	4,715
Depreciation	1,942	1,636
Stock-based compensation	13,819	11,567
Gain on disposal of asset	0	(8)
Change in fair value of derivatives	2,739	(265)
Non-cash changes in the fair value of contingent consideration payable	1,400	5,628
Foreign currency remeasurement (gain)/ loss	2,107	(3,003)
Non-cash deferred taxes	0	98
Changes in operating assets and liabilities:
Accounts receivable	(6,043)	(2,226)
Inventories	(3,449)	(351)
Prepaid expenses and other current assets	4,584	(2,103)
Other non-current assets	(793)	(515)
Account payable and accrued expenses	(11,801)	(4,297)
Non-current liabilities	457	496
Deferred reimbursement	(5,000)	0
Net cash used in operating activities	(106,516)	(91,757)
Investing activities
Sale and redemption of marketable securities	210,239	137,909
Purchases of marketable securities	(380,234)	(184,494)
Capital expenditures	(1,881)	(2,279)
Net cash used in investing activities	(171,876)	(48,864)
Financing activities
Proceeds from issuance of common stock, net of issuance costs	294,584	0
Payment of capital leases	(142)	(142)
Payment of contingent consideration	0	(10,000)
Purchase of vested restricted stock units	(2,027)	(1,003)
Proceeds from exercise of stock options	7,580	1,554
Payment of deferred financing fees	0	(28)
Proceeds of exercise of warrants	3,617	0
Net cash provided by (used in) financing activities	303,612	(9,619)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,016)	614
Net increase (decrease) in cash and cash equivalents and restricted cash	24,204	(149,626)
Cash and cash equivalents and restricted cash at beginning of period	51,237	187,413
Cash and cash equivalents and restricted cash at end of period	75,441	37,787
Supplemental disclosures of cash flow information
Cash paid during the period for interest	3,774	3,650
Capital expenditures, unpaid	0	351
Capital expenditures funded by capital lease	$ 81	$ 0

Description of Business	6 Months Ended
Description of Business	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Amicus Therapeutics, Inc. (the “Company”) is a global patient-centric biotechnology company engaged in the discovery, development and commercialization of a diverse set of novel treatments for patients living with rare metabolic diseases. The cornerstone of the Company’s portfolio is migalastat HCl (also referred to as “migalastat”), an oral precision medicine for people living with Fabry disease who have amenable genetic mutations. Migalastat is currently approved under the trade name GALAFOLD in the European Union (“EU”) and Japan, with additional approvals granted and applications pending in several geographies. During the second quarter of 2018, the Company initiated the commercial launch of GALAFOLD in Japan for the treatment of patients, aged 16 and older, with a confirmed diagnosis of Fabry disease and an amenable mutation. GALAFOLD is the first and only oral precision medicine approved for the treatment of Fabry disease in Japan. The lead biologics program of the Company’s pipeline is Amicus Therapeutics GAA (AT-GAA, also known as ATB200/AT2221), a novel, clinical-stage, potential best-in-class treatment paradigm for Pompe disease. The Company’s Chaperone-Advanced Replacement Therapy (“CHART®”) platform technology is leveraged to develop novel Enzyme Replacement Therapy (“ERT”) products for Pompe disease, Fabry disease, and potentially future other lysosomal storage disorders (“LSDs”). The Company is also investigating preclinical and discovery programs in other rare diseases including cyclin-dependent kinase-like 5 (“CDKL5”) deficiency. The Company believes that its platform technologies and its product pipeline uniquely positions it and drives its commitment to advancing and expanding a robust pipeline of cutting-edge, first- or best-in-class medicines for rare metabolic diseases. During the first quarter of 2018, the Company issued 20,239,839 shares of its common stock through an underwritten offering resulting in net proceeds of $294.6 million after deducting underwriting discounts and commissions and offering expenses payable by the Company. The Company expects to use the net proceeds of the offering for investment in the United States (“U.S.”) and international commercial infrastructure for migalastat HCl, investment in manufacturing capabilities for the ERT ATB200, the continued clinical development of its product candidates, research and development expenditures, clinical and pre-clinical trial expenditures, commercialization expenditures and for other general corporate purposes. For additional information, see “—Note 6. Stockholders’ Equity.” The Company had an accumulated deficit of approximately $1.2 billion as of June 30, 2018 and anticipates incurring losses through the fiscal year ending December 31, 2018 and beyond. The Company has been able to fund its operating losses to date through stock offerings, debt issuances, payments from partners during the terms of the collaboration agreements, and other financing arrangements. The current cash position, including proceeds from the equity offering in the first quarter of 2018 and expected GALAFOLD revenues, is sufficient to fund ongoing Fabry and Pompe program operations into at least 2021. Potential future business development collaborations, pipeline expansion, and investment in biologics manufacturing capabilities could impact the Company’s future capital requirements.

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The Company has prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information. The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the Company’s financial statements and related notes as contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017. For a complete description of the Company’s accounting policies, please refer to the Annual Report on Form 10-K for the fiscal year ended December 31, 2017. Consolidation The consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions have been 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 stockholders’ equity. 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, Cash Equivalents, Restricted Cash 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 consolidated 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. Restricted cash consists primarily of funds held to satisfy the requirements of certain agreements that are restricted in their use and is included in non-current assets on the Company’s consolidated balance sheet. 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 Company’s accounts receivable at June 30, 2018 have arisen from product sales primarily in the EU. 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. Revenue Recognition The Company’s net product sales consist of sales of GALAFOLD for the treatment of Fabry disease primarily 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 (“EAP”). Orders for GALAFOLD are generally received from pharmacies and the ultimate payor is typically a government authority. The Company recognizes revenue when its performance obligations to its customers have been satisfied, which occurs at a point in time when the pharmacies or distributors obtain control of GALAFOLD. The transaction price is determined based on fixed consideration in the Company’s customer contracts and is recorded net of estimates for variable consideration, which are third party discounts and rebates. The identified variable consideration is recorded as a reduction of revenue at the time revenues from sales of GALAFOLD are recognized. The Company recognizes revenue to the extent that it is probable that a significant revenue reversal will not occur in a future period. These estimates may differ from actual consideration received. The Company evaluates these estimates each reporting period to reflect known changes. The Company elected the portfolio approach practical expedient in applying ASC Topic 606 to its identified revenue streams. Contracts within each revenue stream have similar characteristics and the Company believes this approach would not differ materially from applying ASC Topic 606 to each individual contract. Recent Accounting Developments - Guidance Adopted in 2018 ASU 2018-07 — In June 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2018-07,Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07").These amendments expand the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees, and is effective for all public entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, but no earlier than a company’s adoption date of Topic 606, Revenue from Contracts with Customers. The Company early adopted ASU 2018-07 in the second quarter of 2018 and there was no material impact on its consolidated financial statements from the adoption. ASU 2018-02 — In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU No. 2018-02”). Prior to ASU No. 2018-02, U.S. GAAP required the remeasurement of deferred tax assets and liabilities as a result of a change in tax laws or rates to be presented in net income from continuing operations, even in situations in which the related income tax effects of items in accumulated other comprehensive income were originally recognized in other comprehensive income. As a result, such items, referred to as stranded tax effects, did not reflect the appropriate tax rate. Under ASU No. 2018-02, entities are permitted, but not required, to reclassify from accumulated other comprehensive income to retained earnings those stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. ASU No. 2018-02 is effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted the new standard effective January 1, 2018. As a result of the adoption, the Company reclassified a gain of $383,000 from the foreign currency translation adjustment in accumulated other comprehensive loss to accumulated deficit in the consolidated balance sheet as of June 30, 2018. ASU 2017-09 — In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). The amendments in ASU 2017-09 provide guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under ASU 2017-09. An entity should account for the effects of a modification unless all the following are met: (1) The fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification; (2) The vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and (3) The classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. ASU 2017-09 is effective for all entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted this standard on January 1, 2018 and as the Company did not have any modification of awards, the adoption of the standard did not have a material impact on its consolidated financial statements. ASU 2017-01 — In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”). This ASU 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 ASU 2017-01 are effective for public companies for annual periods beginning after December 15, 2017, including interim periods within those periods. The amendments should be applied prospectively as of the beginning of the period of adoption. The Company adopted ASU 2017-01 on January 1, 2018 and as the Company did not have any acquisitions or dispositions in 2018, the adoption of the standard did not have a material impact on its consolidated financial statements. ASU 2016-18 — In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”). The amendments of ASU 2016-18 require an entity to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of ASU 2016-18 are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods. The Company adopted the guidance in ASU 2016-18 effective January 1, 2018. In connection with the adoption of the standard, the Company applied the guidance retrospectively which resulted in an increase in cash flows from operations of $6,000 on the statement of cash flows for the six months ended June 30, 2017. ASU 2016-16 — In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 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 ASU 2016-16 are effective for public business entities for annual periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The Company adopted ASU 2016-16 on January 1, 2018 and there was no material impact from the adoption. ASU 2016-01 — In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 changes accounting for equity investments, financial liabilities under the fair value option, and presentation and disclosure requirements for financial instruments. ASU 2016-01 does not apply to equity investments in consolidated subsidiaries or those accounted for under the equity method of accounting. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. Equity investments with readily determinable fair values will be measured at fair value with changes in fair value recognized in net income. Companies have the option to measure equity investments without readily determinable fair values at either fair value or at cost adjusted for changes in observable prices minus impairment. Companies that elect the fair value option for financial liabilities must recognize changes in fair value related to instrument-specific credit risk in other comprehensive income. Companies must assess valuation allowances for deferred tax assets related to available-for-sale debt securities in combination with their other deferred tax assets. ASU 2016-01 is effective beginning in the first quarter of 2018 and the Company adopted it in the first quarter of 2018. There was no impact on the Company’s consolidated financial statements and related disclosures upon adoption, as the Company does not have equity investments or liabilities with credit risk. In addition, the guidance relating to deferred tax assets did not result in a change in accounting treatment for the Company. ASU 2014-09 — In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) which along with amendments issued in 2015 and 2016, replaced substantially all current U.S. GAAP guidance on this topic and eliminated industry-specific guidance. The new revenue recognition standard requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Effective January 1, 2018, the Company adopted the new revenue recognition standard using the modified retrospective approach and applied this approach only to contracts that were not completed as of January 1, 2018. The timing of revenue recognition and treatment of contract costs remains unchanged under the new revenue recognition standard. As such, the adoption of the new revenue recognition standard did not have a material impact on the Company's consolidated financial statements. The information presented for the periods prior to January 1, 2018 has not been restated and is reported under the accounting standard in effect for those periods. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2017-12 — In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”). The amendments in this ASU 2017-12 better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. To meet that objective, the amendments expand and refine hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The amendments in ASU 2017-12 also make certain targeted improvements to simplify the application of hedge accounting guidance and ease the administrative burden of hedge documentation requirements and assessing hedge effectiveness. For public business entities, the amendment is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption, including adoption in an interim period, is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. ASU 2017-11 — In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I of ASU 2017-11 addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. When determining whether certain financial instruments should be classified as liabilities or equity instruments, a down round feature no longer precludes equity classification when assessing whether the instrument is indexed to an entity’s own stock. Part II of ASU 2017-11 addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of extensive pending content in the FASB Accounting Standards Codification®. For public business entities, the amendments in Part I of ASU 2017-11 are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted for all entities, including adoption in an interim period. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. ASU 2017-08 — In March 2017, the FASB issued ASU 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”). The amendments in ASU 2017-08 shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. ASU 2017-08 is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. The amendments should be applied on a modified retrospective basis, with a cumulative-effect adjustment directly to retained earnings 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. ASU 2017-04 — In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). 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. ASU 2016-02 — In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires the recognition of lease assets and lease liabilities on the balance sheet for all lease obligations and disclosing key information about leasing arrangements. ASU 2016-02 requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous generally accepted accounting principles. ASU 2016-02 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.

Cash, Cash Equivalents, Marketable Securities and Restricted Cash

6 Months Ended

Jun. 30, 2018

Cash, Cash Equivalents, and Short-term Investments [Abstract]

Cash, Cash Equivalents, Marketable Securities and Restricted Cash

As of June 30, 2018, the Company held $73.3 million in cash and cash equivalents and $479.5 million of available-for-sale debt 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.

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 greater than three months but less than one year are classified as current, while investments that have maturities greater than one year are classified as long-term.

Cash, cash equivalents and marketable securities are classified as current unless mentioned otherwise below and consisted of the following:



	As of June 30, 2018
(in thousands)	Cost		Gross unrealized Gain		Gross unrealized Loss			Fair Value
Cash and cash equivalents	$	73,311	$	—	$	—		$	73,311
Corporate debt securities, current portion	271,855		—		(326		)	271,529
Corporate debt securities, non-current portion	13,875		—		(38		)	13,837
Commercial paper	144,726		15		(43		)	144,698
Asset-backed securities	49,077		—		(64		)	49,013
Money market	350		—		—			350
Certificates of deposit	50		—		—			50
	$	553,244	$	15	$	(471	)	$	552,788
Included in cash and cash equivalents	$	73,311	$	—	$	—		$	73,311
Included in marketable securities, current and non-current	479,933		15		(471		)	479,477
Total cash, cash equivalents and marketable securities	$	553,244	$	15	$	(471	)	$	552,788



	As of December 31, 2017
(in thousands)	Cost		Gross unrealized Gain		Gross unrealized Loss			Fair Value
Cash and cash equivalents	$	49,060	$	—	$	—		$	49,060
Corporate debt securities, current portion	199,314		1		(303		)	199,012
Commercial paper	79,878		—		(75		)	79,803
Asset-backed securities	30,346		0		(59		)	30,287
Money market	350		—		—			350
Certificates of deposit	50		—		—			50
	$	358,998	$	1	$	(437	)	$	358,562
Included in cash and cash equivalents	$	49,060	$	—	$	—		$	49,060
Included in marketable securities	309,938		1		(437		)	309,502
Total cash, cash equivalents and marketable securities	$	358,998	$	1	$	(437	)	$	358,562

For the six months ended June 30, 2018 and the fiscal year ended December 31, 2017, 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 debt securities as of June 30, 2018 and December 31, 2017 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 debt securities in unrealized loss positions was $406.5 million and $295.1 million as of June 30, 2018 and December 31, 2017, respectively.

The following table provides a reconciliation of cash and cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same such amounts shown in the statement of cash flows.



(in thousands)	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Cash and cash equivalents	$	73,311	$	49,060	$	37,394	$	187,026
Restricted cash	2,130		2,177		393		387
Cash and cash equivalents and restricted cash shown in the statement of cash flows	$	75,441	$	51,237	$	37,787	$	187,413

Inventories

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

Inventories

Inventories consist of work in process and finished goods related to the manufacture of GALAFOLD. The following table summarizes the components of inventories:



(in thousands)	June 30, 2018		December 31, 2017
Work-in-process	$	5,506	$	3,843
Finished goods	2,263		780
Total inventories	$	7,769	$	4,623

Debt

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Debt

Convertible Notes due 2023

In December 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 Convertible Notes in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act (the “Note Offering”). Interest is payable semiannually on June 15 and December 15 of each year, beginning on June 15, 2017. The Convertible Notes will mature on December 15, 2023, unless earlier repurchased, redeemed, or converted in accordance with their terms. The Convertible 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. The net proceeds from the Note Offering were $243.0 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. 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 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 the Company's common stock, subject to adjustment under certain conditions. The last reported sale price of the Company’s common stock was equal to or more than 130% of the conversion price of the Convertible Notes for at least 20 trading days of the 30 consecutive trading days ending on the last day of the second quarter. As a result, the Convertible Notes are currently convertible into the Company’s common stock.

As further described in “—Note 6. Stockholders’ Equity,” on February 15, 2018, the Company entered into an underwriting agreement relating to an underwritten public offering of 19,354,839 shares of the Company’s common stock. Under the terms of the underwriting agreement, the Company granted the underwriters an option, exercisable for 30 days after February 16, 2018, to purchase up to an additional 2,903,225 shares of the Company’s common stock, which was exercised with respect to 885,000 shares of the Company’s common stock.

Subsequent to the underwritten public offering on February 15, 2018, the Company did not have sufficient unissued authorized shares to cover a conversion of the Convertible Notes. As a result, the Company accounted for the portion of the bifurcated conversion feature and of the Capped Call Confirmations that would not be able to be net share settled as a current derivative liability and as a derivative asset, respectively. The fair value of the derivative liability for the conversion feature and derivative asset for the Capped Call Confirmations at February 15, 2018 was determined to be $507.4 million and $13.6 million, respectively, of which the portion that was determined to not be able to be net share settled was recorded with a corresponding impact to additional-paid-in-capital. Subsequent changes to fair value of the derivatives were recorded through earnings on the Company’s consolidated statements of operations resulting in a change in fair value of derivatives for the three and six months ended June 30, 2018 of $(7.6) million and $(2.7) million, respectively.

Following the approval by the stockholders of the Company on June 7, 2018, to increase the authorized shares of common stock to 500,000,000, the Company has sufficient unissued authorized shares to cover a conversion of the Convertible Notes. As a result, the derivative liability and derivative asset were reclassified into additional-paid-in-capital. The fair value of the derivative liability for the conversion feature and derivative asset for the Capped Call Confirmations at June 7, 2018 was determined to be $88.3 million and $2.4 million, respectively.

The Convertible Notes consist of the following (in thousands):



Liability component	June 30, 2018			December 31, 2017
Principal	$	250,000		$	250,000
Less: debt discount (1)	(76,555		)	(81,566		)
Less: deferred financing (1)	(4,005		)	(4,267		)
Net carrying value of the debt	$	169,440		$	164,167

______________________________________

(1) Included in the consolidated balance sheets within convertible notes and amortized to interest expense over the remaining life of the convertible notes using the effective interest rate method.

The following table sets forth total interest expense recognized related to the Convertible Notes for the three and six months ended June 30, 2018, respectively:



Components (In thousands)	Three months ended June 30, 2018		Six months ended June 30, 2018
Contractual interest expense	$	1,888	$	3,775
Amortization of debt discount	2,539		5,011
Amortization of deferred financing	133		262
Total	$	4,560	$	9,048

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock and Warrants On February 15, 2018, the Company announced the pricing of an underwritten offering of 19,354,839 shares of its common stock at $15.50 per share, resulting in gross proceeds of $300.0 million. Under the terms of the underwriting agreement, the Company granted the underwriters an option, exercisable for 30 days after February 16, 2018, to purchase up to an additional 2,903,225 shares of the Company’s common stock, which was exercised with respect to 885,000 shares of the Company’s common stock at a purchase price of $15.50 per share. The Company received net proceeds of $294.6 million from these offerings, after deducting underwriting discounts and commissions and offering expenses payable by the Company. In April 2018, 453,214 warrants were exercised at $7.98 per share of common stock resulting in gross cash proceeds of $3.6 million. On June 7, 2018, the Company’s stockholders approved an amendment to the Company’s Restated Certificate of Incorporation to increase the number of shares of common stock, par value $0.01 per share, that the Company is authorized to issue from 250,000,000 shares to 500,000,000 shares.

Share based Compensation (Notes)

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share based Compensation

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 units 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. 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.

Stock Option Grants

The fair value of the stock options granted is estimated on the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Expected stock price volatility	81.1		%	82.7		%	81.2		%	83.2		%
Risk free interest rate	2.8		%	1.9		%	2.4		%	2.0		%
Expected life of options (years)	5.62			6.25			5.62			6.25
Expected annual dividend per share	$	—		$	—		$	—		$	—

Beginning in the third quarter of 2017, the average expected life was determined using our actual historical data versus a “simplified” method used in prior quarters. The “simplified” method of estimating the expected exercise term uses the mid-point between the vesting date and the end of the contractual term. In earlier quarters, we did not have sufficient reliable exercise data to justify a change from the use of the “simplified” method of estimating the expected exercise term of employee stock option grants. The impact from this change was not material.

A summary of the Company’s stock options for the six months ended June 30, 2018 were as follows:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value
	(in thousands)					(in millions)
Options outstanding, December 31, 2017	15,181		$	7.48
Granted	1,910		$	15.49
Exercised	(1,102	)	$	6.87
Forfeited	(113	)	$	9.75
Expired	(7	)	10.45
Options outstanding, June 30, 2018	15,869		$	8.47	7.2 years	$	114.0
Vested and unvested expected to vest, June 30, 2018	15,160		$	8.32	7.1 years	$	109.6
Exercisable at June 30, 2018	8,916		$	7.08	6.1 years	$	76.4

As of June 30, 2018, the total unrecognized compensation cost related to non-vested stock options granted was $39.1 million and is expected to be recognized over a weighted average period of three years.

Restricted Stock Units (“RSUs”) and Performance-Based 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 six months ended June 30, 2018 is as follows:



	Number of Shares		Weighted Average Grant Date Fair Value		Weighted Average Remaining Years	Aggregate Intrinsic Value
	(in thousands)					(in millions)
Non-vested units as of December 31, 2017	2,575		$	5.85
Granted	1,522		$	16.77
Vested	(511	)	$	5.82
Forfeited	(30	)	$	7.96
Non-vested units as of June 30, 2018	3,556		$	10.39	2.9 years	$	55.5

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. Certain awards under the Performance-Based RSU Agreement were granted in January 2017 and 2018. The 2018 grants include 187,222 market performance-based restricted stock units (“MPRSUs”) granted to executives. Vesting of these awards is contingent upon the Company meeting certain total shareholder return (“TSR”) levels as compared to a select peer group over the next three years. The MPRSUs cliff vest at the end of the three-year period and have a maximum potential to vest at 200% (374,444 shares) based on TSR performance. The related share-based compensation expense is determined based on the estimated fair value of the underlying shares on the date of grant and is recognized on a straight-line basis over the vesting term. The estimated fair value per share of the MPRSUs was $25.44 and was calculated using a Monte Carlo simulation model. The awards also include 187,211 performance based awards that will vest over the next three years based on the Company achieving certain clinical milestones. During the six months ended June 30, 2018, none of the clinical milestones for the performance based RSUs awarded in 2017 or 2018 were reached.

For the six months ended June 30, 2018, 510,695 RSUs have vested and all non-vested units are expected to vest over their normal term. As of June 30, 2018, there was $25.6 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 three years.

Compensation Expense Related to Equity Awards

The following table summarizes information related to compensation expense recognized in the statements of operations related to the equity awards:



	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2018		2017		2018		2017
Equity compensation expense recognized in:
Research and development expense	$	2,641	$	2,313	$	5,698	$	5,066
Selling, general and administrative expense	3,700		3,224		8,121		6,501
Total equity compensation expense	$	6,341	$	5,537	$	13,819	$	11,567

Assets and Liabilities Measured at Fair Value

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

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 June 30, 2018 are identified in the following table:



(in thousands)	Level 2		Total
Assets:
Commercial paper	$	144,698	$	144,698
Asset-backed securities	49,013		49,013
Corporate debt securities	285,366		285,366
Money market funds	3,081		3,081
	$	482,158	$	482,158



	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	26,800	$	26,800
Deferred compensation plan liability	2,731		—		2,731
	$	2,731	$	26,800	$	29,531

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, 2017 are identified in the following table:



(in thousands)	Level 2		Total
Assets:
Commercial paper	$	79,803	$	79,803
Asset-backed securities	30,287		30,287
Corporate debt securities	199,012		199,012
Money market funds	2,598		2,598
	$	311,700	$	311,700



	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	25,400	$	25,400
Deferred compensation plan liability	2,258		—		2,258
	$	2,258	$	25,400	$	27,658

The Company’s Convertible Notes fall into the Level 2 category within the fair value level hierarchy. The fair value was determined using broker quotes in a non-active market for valuation. The fair value of the debt at June 30, 2018 was approximately $666.2 million.

The Company did not have any Level 3 assets as of June 30, 2018 or December 31, 2017.

Cash, Money Market Funds and Marketable Securities

The Company classifies its cash within the fair value hierarchy as Level 1 as these assets are valued using quoted prices in an active market for identical assets at the measurement date. The Company considers its investments in marketable securities as available for sale debt securities and classifies these assets and the money market funds 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 six months ended June 30, 2018. No transfers of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the six months ended June 30, 2018.

Contingent Consideration Payable

The contingent consideration payable resulted from the acquisition of Callidus Biopharma, Inc. ("Callidus") in November 2013. 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.

The contingent consideration payable for 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.

The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Callidus for the ATB200 Pompe program:



Contingent Consideration Liability	Fair Value as of June 30, 2018			Valuation Technique	Unobservable Input	Range

					Discount rate	11.0%

Clinical and regulatory milestones	$	26.3	million	Probability weighted discounted cash flow	Probability of achievement of milestones	71.0%-100.0%

					Projected year of payments	2018-2022

Contingent consideration liabilities are remeasured to fair value each reporting period using 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. 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 three and six months ended June 30, 2018 and 2017, respectively:



	Three Months Ended June 30,					Six Months Ended June 30,
(in thousands)	2018		2017			2018	2017
Balance, beginning of the period	$	26,500	$	274,300		25,400	269,722
Payment of contingent consideration in cash	—		(10,000		)	—	(10,000		)
Changes in fair value during the period, included in statement of operations	300		1,050			1,400	5,628
Balance, end of the period	$	26,800	$	265,350		26,800	$	265,350

Deferred Compensation Plan - Investment and Liability

The Deferred Compensation Plan (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 investment’s 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.

- 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

Basic and Diluted Net Loss per Common Share

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Basic and Diluted Net Loss per Common Share

The following table provides a reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share:



	Three Months Ended June 30,						Six Months Ended June 30,
(in thousands, except per share amounts)	2018			2017			2018			2017
Numerator:
Net loss attributable to common stockholders	$	(61,833	)	$	(48,136	)	$	(111,751	)	$	(103,129	)
Denominator:
Weighted average common shares outstanding — basic and diluted	188,621,423			143,000,718			182,303,128			142,886,614

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.

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:



	As of June 30,
(in thousands)	2018	2017
Options to purchase common stock	15,869	17,275
Convertible debt	40,850	40,850
Outstanding warrants, convertible to common stock	2,657	3,110
Unvested restricted stock units	3,556	2,826
Vested restricted stock units, unissued	111	50
Total number of potentially issuable shares	63,043	64,111

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Basis of Presentation	Basis of Presentation The Company has prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10-01 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, the accompanying unaudited financial statements reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s interim financial information. The accompanying unaudited consolidated financial statements and related notes should be read in conjunction with the Company’s financial statements and related notes as contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017. For a complete description of the Company’s accounting policies, please refer to the Annual Report on Form 10-K for the fiscal year ended December 31, 2017.
Consolidation	Consolidation The consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation.
Foreign Currency Transactions	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 stockholders’ equity.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates.
Cash, Cash Equivalents, Restricted Cash and Marketable Securities	Cash, Cash Equivalents, Restricted Cash 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 consolidated 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. Restricted cash consists primarily of funds held to satisfy the requirements of certain agreements that are restricted in their use and is included in non-current assets on the Company’s consolidated balance sheet.
Concentration of Credit Risk	Concentration of Credit Risk The Company’s financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company maintains its cash and cash equivalents in bank accounts, which, at times, exceed federally insured limits. The Company invests its marketable securities in high-quality commercial financial instruments. The Company has not recognized any losses from credit risks on such accounts during any of the periods presented. The Company believes it is not exposed to significant credit risk on cash and cash equivalents or its marketable securities. The Company is subject to credit risk from its accounts receivable related to its product sales of GALAFOLD. The Company’s accounts receivable at June 30, 2018 have arisen from product sales primarily in the EU. 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.
Revenue Recognition	Revenue Recognition The Company’s net product sales consist of sales of GALAFOLD for the treatment of Fabry disease primarily 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 (“EAP”). Orders for GALAFOLD are generally received from pharmacies and the ultimate payor is typically a government authority. The Company recognizes revenue when its performance obligations to its customers have been satisfied, which occurs at a point in time when the pharmacies or distributors obtain control of GALAFOLD. The transaction price is determined based on fixed consideration in the Company’s customer contracts and is recorded net of estimates for variable consideration, which are third party discounts and rebates. The identified variable consideration is recorded as a reduction of revenue at the time revenues from sales of GALAFOLD are recognized. The Company recognizes revenue to the extent that it is probable that a significant revenue reversal will not occur in a future period. These estimates may differ from actual consideration received. The Company evaluates these estimates each reporting period to reflect known changes. The Company elected the portfolio approach practical expedient in applying ASC Topic 606 to its identified revenue streams. Contracts within each revenue stream have similar characteristics and the Company believes this approach would not differ materially from applying ASC Topic 606 to each individual contract.
Recent Accounting Developments	Recent Accounting Developments - Guidance Adopted in 2018 ASU 2018-07 — In June 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2018-07,Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07").These amendments expand the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees, and is effective for all public entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, but no earlier than a company’s adoption date of Topic 606, Revenue from Contracts with Customers. The Company early adopted ASU 2018-07 in the second quarter of 2018 and there was no material impact on its consolidated financial statements from the adoption. ASU 2018-02 — In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU No. 2018-02”). Prior to ASU No. 2018-02, U.S. GAAP required the remeasurement of deferred tax assets and liabilities as a result of a change in tax laws or rates to be presented in net income from continuing operations, even in situations in which the related income tax effects of items in accumulated other comprehensive income were originally recognized in other comprehensive income. As a result, such items, referred to as stranded tax effects, did not reflect the appropriate tax rate. Under ASU No. 2018-02, entities are permitted, but not required, to reclassify from accumulated other comprehensive income to retained earnings those stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. ASU No. 2018-02 is effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted the new standard effective January 1, 2018. As a result of the adoption, the Company reclassified a gain of $383,000 from the foreign currency translation adjustment in accumulated other comprehensive loss to accumulated deficit in the consolidated balance sheet as of June 30, 2018. ASU 2017-09 — In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). The amendments in ASU 2017-09 provide guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under ASU 2017-09. An entity should account for the effects of a modification unless all the following are met: (1) The fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification; (2) The vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and (3) The classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. ASU 2017-09 is effective for all entities for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted this standard on January 1, 2018 and as the Company did not have any modification of awards, the adoption of the standard did not have a material impact on its consolidated financial statements. ASU 2017-01 — In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”). This ASU 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 ASU 2017-01 are effective for public companies for annual periods beginning after December 15, 2017, including interim periods within those periods. The amendments should be applied prospectively as of the beginning of the period of adoption. The Company adopted ASU 2017-01 on January 1, 2018 and as the Company did not have any acquisitions or dispositions in 2018, the adoption of the standard did not have a material impact on its consolidated financial statements. ASU 2016-18 — In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”). The amendments of ASU 2016-18 require an entity to include amounts generally described as restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of ASU 2016-18 are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods. The Company adopted the guidance in ASU 2016-18 effective January 1, 2018. In connection with the adoption of the standard, the Company applied the guidance retrospectively which resulted in an increase in cash flows from operations of $6,000 on the statement of cash flows for the six months ended June 30, 2017. ASU 2016-16 — In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). ASU 2016-16 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 ASU 2016-16 are effective for public business entities for annual periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The Company adopted ASU 2016-16 on January 1, 2018 and there was no material impact from the adoption. ASU 2016-01 — In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). ASU 2016-01 changes accounting for equity investments, financial liabilities under the fair value option, and presentation and disclosure requirements for financial instruments. ASU 2016-01 does not apply to equity investments in consolidated subsidiaries or those accounted for under the equity method of accounting. In addition, the FASB clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. Equity investments with readily determinable fair values will be measured at fair value with changes in fair value recognized in net income. Companies have the option to measure equity investments without readily determinable fair values at either fair value or at cost adjusted for changes in observable prices minus impairment. Companies that elect the fair value option for financial liabilities must recognize changes in fair value related to instrument-specific credit risk in other comprehensive income. Companies must assess valuation allowances for deferred tax assets related to available-for-sale debt securities in combination with their other deferred tax assets. ASU 2016-01 is effective beginning in the first quarter of 2018 and the Company adopted it in the first quarter of 2018. There was no impact on the Company’s consolidated financial statements and related disclosures upon adoption, as the Company does not have equity investments or liabilities with credit risk. In addition, the guidance relating to deferred tax assets did not result in a change in accounting treatment for the Company. ASU 2014-09 — In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) which along with amendments issued in 2015 and 2016, replaced substantially all current U.S. GAAP guidance on this topic and eliminated industry-specific guidance. The new revenue recognition standard requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Effective January 1, 2018, the Company adopted the new revenue recognition standard using the modified retrospective approach and applied this approach only to contracts that were not completed as of January 1, 2018. The timing of revenue recognition and treatment of contract costs remains unchanged under the new revenue recognition standard. As such, the adoption of the new revenue recognition standard did not have a material impact on the Company's consolidated financial statements. The information presented for the periods prior to January 1, 2018 has not been restated and is reported under the accounting standard in effect for those periods. Recent Accounting Developments - Guidance Not Yet Adopted ASU 2017-12 — In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”). The amendments in this ASU 2017-12 better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. To meet that objective, the amendments expand and refine hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The amendments in ASU 2017-12 also make certain targeted improvements to simplify the application of hedge accounting guidance and ease the administrative burden of hedge documentation requirements and assessing hedge effectiveness. For public business entities, the amendment is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption, including adoption in an interim period, is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. ASU 2017-11 — In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I of ASU 2017-11 addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. When determining whether certain financial instruments should be classified as liabilities or equity instruments, a down round feature no longer precludes equity classification when assessing whether the instrument is indexed to an entity’s own stock. Part II of ASU 2017-11 addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of extensive pending content in the FASB Accounting Standards Codification®. For public business entities, the amendments in Part I of ASU 2017-11 are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted for all entities, including adoption in an interim period. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. ASU 2017-08 — In March 2017, the FASB issued ASU 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”). The amendments in ASU 2017-08 shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. ASU 2017-08 is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. The amendments should be applied on a modified retrospective basis, with a cumulative-effect adjustment directly to retained earnings 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. ASU 2017-04 — In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). 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. ASU 2016-02 — In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires the recognition of lease assets and lease liabilities on the balance sheet for all lease obligations and disclosing key information about leasing arrangements. ASU 2016-02 requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous generally accepted accounting principles. ASU 2016-02 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.

Cash, Cash Equivalents, Marketable Securities and Restricted Cash (Tables)

6 Months Ended

Jun. 30, 2018

Cash, Cash Equivalents, and Short-term Investments [Abstract]

Schedule of cash and available-for-sale securities



(in thousands)	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Cash and cash equivalents	$	73,311	$	49,060	$	37,394	$	187,026
Restricted cash	2,130		2,177		393		387
Cash and cash equivalents and restricted cash shown in the statement of cash flows	$	75,441	$	51,237	$	37,787	$	187,413

Cash, cash equivalents and marketable securities are classified as current unless mentioned otherwise below and consisted of the following:



	As of June 30, 2018
(in thousands)	Cost		Gross unrealized Gain		Gross unrealized Loss			Fair Value
Cash and cash equivalents	$	73,311	$	—	$	—		$	73,311
Corporate debt securities, current portion	271,855		—		(326		)	271,529
Corporate debt securities, non-current portion	13,875		—		(38		)	13,837
Commercial paper	144,726		15		(43		)	144,698
Asset-backed securities	49,077		—		(64		)	49,013
Money market	350		—		—			350
Certificates of deposit	50		—		—			50
	$	553,244	$	15	$	(471	)	$	552,788
Included in cash and cash equivalents	$	73,311	$	—	$	—		$	73,311
Included in marketable securities, current and non-current	479,933		15		(471		)	479,477
Total cash, cash equivalents and marketable securities	$	553,244	$	15	$	(471	)	$	552,788



	As of December 31, 2017
(in thousands)	Cost		Gross unrealized Gain		Gross unrealized Loss			Fair Value
Cash and cash equivalents	$	49,060	$	—	$	—		$	49,060
Corporate debt securities, current portion	199,314		1		(303		)	199,012
Commercial paper	79,878		—		(75		)	79,803
Asset-backed securities	30,346		0		(59		)	30,287
Money market	350		—		—			350
Certificates of deposit	50		—		—			50
	$	358,998	$	1	$	(437	)	$	358,562
Included in cash and cash equivalents	$	49,060	$	—	$	—		$	49,060
Included in marketable securities	309,938		1		(437		)	309,502
Total cash, cash equivalents and marketable securities	$	358,998	$	1	$	(437	)	$	358,562

Schedule of restricted cash and cash equivalents



(in thousands)	June 30, 2018		December 31, 2017		June 30, 2017		December 31, 2016
Cash and cash equivalents	$	73,311	$	49,060	$	37,394	$	187,026
Restricted cash	2,130		2,177		393		387
Cash and cash equivalents and restricted cash shown in the statement of cash flows	$	75,441	$	51,237	$	37,787	$	187,413

Inventories (Tables)

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

Schedule of inventories for the period

The following table summarizes the components of inventories:



(in thousands)	June 30, 2018		December 31, 2017
Work-in-process	$	5,506	$	3,843
Finished goods	2,263		780
Total inventories	$	7,769	$	4,623

Debt (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Schedule of liability components of the Convertible Notes

The Convertible Notes consist of the following (in thousands):



Liability component	June 30, 2018			December 31, 2017
Principal	$	250,000		$	250,000
Less: debt discount (1)	(76,555		)	(81,566		)
Less: deferred financing (1)	(4,005		)	(4,267		)
Net carrying value of the debt	$	169,440		$	164,167

______________________________________

(1) Included in the consolidated balance sheets within convertible notes and amortized to interest expense over the remaining life of the convertible 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 three and six months ended June 30, 2018, respectively:



Components (In thousands)	Three months ended June 30, 2018		Six months ended June 30, 2018
Contractual interest expense	$	1,888	$	3,775
Amortization of debt discount	2,539		5,011
Amortization of deferred financing	133		262
Total	$	4,560	$	9,048

Share based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Fair Value of Options

The fair value of the stock options granted is estimated on the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Expected stock price volatility	81.1		%	82.7		%	81.2		%	83.2		%
Risk free interest rate	2.8		%	1.9		%	2.4		%	2.0		%
Expected life of options (years)	5.62			6.25			5.62			6.25
Expected annual dividend per share	$	—		$	—		$	—		$	—

Schedule of Stock Options Activity

A summary of the Company’s stock options for the six months ended June 30, 2018 were as follows:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life	Aggregate Intrinsic Value
	(in thousands)					(in millions)
Options outstanding, December 31, 2017	15,181		$	7.48
Granted	1,910		$	15.49
Exercised	(1,102	)	$	6.87
Forfeited	(113	)	$	9.75
Expired	(7	)	10.45
Options outstanding, June 30, 2018	15,869		$	8.47	7.2 years	$	114.0
Vested and unvested expected to vest, June 30, 2018	15,160		$	8.32	7.1 years	$	109.6
Exercisable at June 30, 2018	8,916		$	7.08	6.1 years	$	76.4

Schedule of Non-Vested RSU Activity under the Plan

A summary of non-vested RSU activity under the Plan for the six months ended June 30, 2018 is as follows:



	Number of Shares		Weighted Average Grant Date Fair Value		Weighted Average Remaining Years	Aggregate Intrinsic Value
	(in thousands)					(in millions)
Non-vested units as of December 31, 2017	2,575		$	5.85
Granted	1,522		$	16.77
Vested	(511	)	$	5.82
Forfeited	(30	)	$	7.96
Non-vested units as of June 30, 2018	3,556		$	10.39	2.9 years	$	55.5

Schedule of Equity Compensation Expenses

The following table summarizes information related to compensation expense recognized in the statements of operations related to the equity awards:



	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2018		2017		2018		2017
Equity compensation expense recognized in:
Research and development expense	$	2,641	$	2,313	$	5,698	$	5,066
Selling, general and administrative expense	3,700		3,224		8,121		6,501
Total equity compensation expense	$	6,341	$	5,537	$	13,819	$	11,567

Assets and Liabilities Measured at Fair Value (Tables)

6 Months Ended

Jun. 30, 2018

Summary of assets and liabilities subject to fair value measurements



(in thousands)	Level 2		Total
Assets:
Commercial paper	$	144,698	$	144,698
Asset-backed securities	49,013		49,013
Corporate debt securities	285,366		285,366
Money market funds	3,081		3,081
	$	482,158	$	482,158



	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	26,800	$	26,800
Deferred compensation plan liability	2,731		—		2,731
	$	2,731	$	26,800	$	29,531



(in thousands)	Level 2		Total
Assets:
Commercial paper	$	79,803	$	79,803
Asset-backed securities	30,287		30,287
Corporate debt securities	199,012		199,012
Money market funds	2,598		2,598
	$	311,700	$	311,700



	Level 2		Level 3		Total
Liabilities:
Contingent consideration payable	$	—	$	25,400	$	25,400
Deferred compensation plan liability	2,258		—		2,258
	$	2,258	$	25,400	$	27,658

Schedule of changes in contingent consideration payable

The following table shows the change in the balance of contingent consideration payable for the three and six months ended June 30, 2018 and 2017, respectively:



	Three Months Ended June 30,					Six Months Ended June 30,
(in thousands)	2018		2017			2018	2017
Balance, beginning of the period	$	26,500	$	274,300		25,400	269,722
Payment of contingent consideration in cash	—		(10,000		)	—	(10,000		)
Changes in fair value during the period, included in statement of operations	300		1,050			1,400	5,628
Balance, end of the period	$	26,800	$	265,350		26,800	$	265,350

Callidus Biopharma Inc

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

The following significant unobservable inputs were used in the valuation of the contingent consideration payable of Callidus for the ATB200 Pompe program:



Contingent Consideration Liability	Fair Value as of June 30, 2018			Valuation Technique	Unobservable Input	Range

					Discount rate	11.0%

Clinical and regulatory milestones	$	26.3	million	Probability weighted discounted cash flow	Probability of achievement of milestones	71.0%-100.0%

					Projected year of payments	2018-2022

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Basic and Diluted Net Loss per Common Share (Tables)

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

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

The following table provides a reconciliation of the numerator and denominator used in computing basic and diluted net loss attributable to common stockholders per common share:



	Three Months Ended June 30,						Six Months Ended June 30,
(in thousands, except per share amounts)	2018			2017			2018			2017
Numerator:
Net loss attributable to common stockholders	$	(61,833	)	$	(48,136	)	$	(111,751	)	$	(103,129	)
Denominator:
Weighted average common shares outstanding — basic and diluted	188,621,423			143,000,718			182,303,128			142,886,614

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:



	As of June 30,
(in thousands)	2018	2017
Options to purchase common stock	15,869	17,275
Convertible debt	40,850	40,850
Outstanding warrants, convertible to common stock	2,657	3,110
Unvested restricted stock units	3,556	2,826
Vested restricted stock units, unissued	111	50
Total number of potentially issuable shares	63,043	64,111

Description of Business (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Description of Business (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of common stock issued from underwriting agreement	20,239,839
Proceeds from issuance of common stock, net of issuance costs	$ 294,600	$ 294,584	$ 0
Retained earnings (accumulated deficit)	$ 383	$ (1,174,978)		$ (1,063,610)

Summary of Significant Accounting Policies - Foreign Currency Transactions (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total stockholders’ equity	$ 561,895			$ 352,850
Retained earnings (accumulated deficit)	(1,174,978)		$ 383	$ (1,063,610)
Net cash used in operating activities	$ (106,516)	$ (91,757)
Accumulated Foreign Currency Adjustment Attributable
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total stockholders’ equity			$ (383)
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in operating activities		$ 6

Cash, Cash Equivalents, Marketable Securities and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash, Money Market Funds, and Marketable Securities
Cash and cash equivalents	$ 73,311	$ 49,060	$ 37,394	$ 187,026
Available-for-sale debt securities	479,477	309,502
Cash balances, Fair Value	73,311	49,060
Cost, available-for-sale securities	479,933	309,938
Gross unrealized gain, available-for-sale securities	15	1
Gross unrealized loss, available-for-sale securities	(471)	(437)
Cost, Cash balances and available-for-sale securities	553,244	358,998
Gross unrealized gain, Cash balances and available-for-sale securities	15	1
Gross unrealized loss, Cash balances and available-for-sale securities	(471)	(437)
Fair value, Cash balances and available-for-sale securities	552,788	358,562
Corporate debt securities, current portion
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	271,529	199,012
Cost, available-for-sale securities	271,855	199,314
Gross unrealized gain, available-for-sale securities	0	1
Gross unrealized loss, available-for-sale securities	(326)	(303)
Corporate debt securities, non-current portion
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	13,837
Cost, available-for-sale securities	13,875
Gross unrealized gain, available-for-sale securities	0
Gross unrealized loss, available-for-sale securities	(38)
Commercial paper
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	144,698	79,803
Cost, available-for-sale securities	144,726	79,878
Gross unrealized gain, available-for-sale securities	15	0
Gross unrealized loss, available-for-sale securities	(43)	(75)
Asset-backed securities
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	49,013	30,287
Cost, available-for-sale securities	49,077	30,346
Gross unrealized gain, available-for-sale securities	0	0
Gross unrealized loss, available-for-sale securities	(64)	(59)
Money market
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	350	350
Cost, available-for-sale securities	350	350
Gross unrealized gain, available-for-sale securities	0	0
Gross unrealized loss, available-for-sale securities	0	0
Certificates of deposit
Cash, Money Market Funds, and Marketable Securities
Available-for-sale debt securities	50	50
Cost, available-for-sale securities	50	50
Gross unrealized gain, available-for-sale securities	0	0
Gross unrealized loss, available-for-sale securities	$ 0	$ 0

Cash, Cash Equivalents, Marketable Securities and Restricted Cash - Additional Information (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Realized gain (loss) on debt securities	$ 0	$ 0
Fair value of available-for-sale debt securities in unrealized loss positions	406,500,000	295,100,000
Cash and cash equivalents	73,311,000	49,060,000	$ 37,394,000	$ 187,026,000
Restricted cash	2,130,000	2,177,000	393,000	387,000
Cash and cash equivalents and restricted cash shown in the statement of cash flows	$ 75,441,000	$ 51,237,000	$ 37,787,000	$ 187,413,000

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Work-in-process	$ 5,506	$ 3,843
Finished goods	2,263	780
Total inventories	$ 7,769	$ 4,623

Debt - Convertible Debt (Details) $ / shares in Units, $ in Thousands				3 Months Ended			6 Months Ended
	Feb. 16, 2018 shares	Feb. 15, 2018 USD ($) shares	Dec. 21, 2016 USD ($) day $ / shares shares	Jun. 30, 2018 USD ($) shares	Mar. 31, 2018 shares	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) shares	Jun. 30, 2017 USD ($)	Jun. 07, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares
Convertible Debt
Number of common stock issued from underwriting agreement \| shares					20,239,839
Derivative liability, noncurrent		$ 507,400
Change in fair value of derivatives				$ (7,600)		$ 0	$ (2,739)	$ 0
Common stock, shares authorized \| shares				500,000,000			500,000,000		500,000,000	250,000,000
Derivative liabilities									$ 88,300
Common Stock Capped Call Confirmation
Convertible Debt
Derivative asset, noncurrent		$ 13,600
Common Stock
Convertible Debt
Number of common stock issued from underwriting agreement \| shares	885,000	19,354,839
Over-allotment Option \| Common Stock
Convertible Debt
Number of days granted underwriters for purchase of shares		30 days
Maximum number of additional shares granted to underwriters \| shares	2,903,225
Convertible Notes
Convertible Debt
Threshold percentage							130.00%
Convertible Notes \| Common Stock Capped Call Confirmation
Convertible Debt
Other assets, current									$ 2,400
Convertible Notes \| Convertible Senior Notes 2016, Due 2023
Convertible Debt
Aggregate principle amount			$ 250,000
Net proceeds after deducting fees and estimated expenses			243,000
Proceeds for capped call confirmations			$ 13,500
shares issued per increment of convertible debt \| shares			40,849,675
Debt conversion ratio (in shares)			0.1633987
Conversion price (in dollars per share) \| $ / shares			$ 6.12
Threshold consecutive trading days \| day			30
Debt Instruments [Abstract]
Principal				$ 250,000			$ 250,000			$ 250,000
Less: debt discount				(76,555)			(76,555)			(81,566)
Less: deferred financing				(4,005)			(4,005)			(4,267)
Net carrying value of the debt				169,440			169,440			$ 164,167
Interest expense
Contractual interest expense				1,888			3,775
Amortization of debt discount				2,539			5,011
Amortization of deferred financing				133			262
Total				$ 4,560			$ 9,048
Convertible Notes \| Convertible Senior Notes 2016, Due 2023 \| Minimum
Convertible Debt
Threshold trading days			20 days
Convertible Notes \| Convertible Senior Notes 2016, Due 2023 \| Over-allotment Option \| Private Placement Purchase Agreement
Convertible Debt
Aggregate principle amount			$ 25,000

Stockholders' Equity - Common Stock and Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 16, 2018	Feb. 15, 2018	Apr. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 07, 2018	Dec. 31, 2017
Collaborative Agreements
Number of common stock issued from underwriting agreement				20,239,839
Net proceeds from the issuance of common stock				$ 294,600	$ 294,584	$ 0
Proceeds of exercise of warrants					$ 3,617	$ 0
Common stock, par value (in dollars per share)					$ 0.01			$ 0.01
Common stock, shares authorized					500,000,000		500,000,000	250,000,000
Outstanding warrants, convertible to common stock
Collaborative Agreements
Number of common stock issued from underwriting agreement			453,214
Proceeds of exercise of warrants			$ 3,600
Common Stock
Collaborative Agreements
Price per share of common stock issued (in dollars per share)		$ 15.50
Gross proceeds from issue of common stock before deducting underwriting discounts and commissions		$ 300,000
Net proceeds from the issuance of common stock					$ 294,600
Common Stock \| Outstanding warrants, convertible to common stock
Collaborative Agreements
Warrants exercise price (in dollars per share)			$ 7.98
Common Stock
Collaborative Agreements
Number of common stock issued from underwriting agreement	885,000	19,354,839
Common Stock \| Over-allotment Option
Collaborative Agreements
Number of days granted underwriters for purchase of shares		30 days
Maximum number of additional shares granted to underwriters	2,903,225

Share based Compensation - Weighted-average Assumptions (Details) - Options to purchase common stock - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected stock price volatility	81.10%	82.70%	81.20%	83.20%
Risk free interest rate	2.80%	1.90%	2.40%	2.00%
Expected life of options (years)	5 years 7 months 15 days	6 years 3 months	5 years 7 months 15 days	6 years 3 months
Expected annual dividend per share (in dollars per share)	$ 0	$ 0	$ 0	$ 0

Share based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Expired (in shares) \| shares	(7)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options, Expired (in dollars per share) \| $ / shares	$ 10.45
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, December 31, 2017 (in shares) \| shares	15,181
Options, Granted (in shares) \| shares	1,910
Options, Exercised (in shares) \| shares	(1,102)
Forfeited, Options (in shares) \| shares	(113)
Options outstanding, June 30, 2018 (in shares) \| shares	15,869
Options, Vested and unvested expected to vest, June 30, 2018 (in shares) \| shares	15,160
Options, Exercisable at June 30, 2018 (in shares) \| shares	8,916
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Option outstanding, December 31, 2017 (in dollars per share) \| $ / shares	$ 7.48
Options, Granted (in dollars per share) \| $ / shares	15.49
Options, Exercised (in dollars per share) \| $ / shares	6.87
Options, Forfeited (in dollars per share) \| $ / shares	9.75
Option outstanding, June 30, 2018 (in dollars per share) \| $ / shares	8.47
Options, Vested and unvested expected to vest, June 30, 2018 (in dollars per share) \| $ / shares	8.32
Options, Exercisable at June 30, 2018 (in shares) \| $ / shares	$ 7.08
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual life, options outstanding, June 30, 2018	7 years 2 months 12 days
Weighted average remaining contractual life, options vested and unvested expected to vest, June 30, 2018	7 years 1 month 6 days
Weighted average remaining contractual life, options exercisable at June 30, 2018	6 years 1 month 6 days
Aggregate intrinsic value, options outstanding, June 30, 2018 \| $	$ 114.0
Aggregate intrinsic value, vested and unvested expected to vest, June 30, 2018 \| $	109.6
Aggregate intrinsic value, exercisable at June 30, 2018 \| $	$ 76.4

Share based Compensation - RSUs and PBRSUs Summary (Details) - Stock Option Plan Amended Restated 2007 Equity Incentive Plan - Unvested restricted stock units $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested units as of December 31, 2017 (in shares) \| shares	2,575,000
Granted (in shares) \| shares	1,522,000
Vested (in shares) \| shares	(510,695)
Forfeited (in shares) \| shares	(30,000)
Non-vested units as of June 30, 2018 (in shares) \| shares	3,556,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Non-vested units as of December 31, 2017 (in dollars per share) \| $ / shares	$ 5.85
Granted (in dollars per share) \| $ / shares	16.77
Vested (in dollars per share) \| $ / shares	5.82
Forfeited (in dollars per share) \| $ / shares	7.96
Non-vested units as of June 30, 2018 (in dollars per share) \| $ / shares	$ 10.39
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Non-vested units, weighted average remaining years	2 years 11 months 1 day
Non-vested units, aggregate intrinsic value \| $	$ 55.5

Share based Compensation - Narrative (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs \| $	$ 39.1
Unrecognized compensation costs, period for recognition	3 years
MPRSUs, Exercisable at period end (in shares)	8,916,000
Market Performance Based Restricted Stock Units \| Stock Option Plan Amended Restated 2007 Equity Incentive Plan \| Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market performance-based restricted stock units granted (in shares)	187,222
Award vesting period	3 years
MPRSUs granted, weighted average exercise price (in dollars per share) \| $ / shares	$ 25.44
Market Performance Based Restricted Stock Units \| Stock Option Plan Amended Restated 2007 Equity Incentive Plan \| Executive Officer \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights (as a percentage)	200.00%
MPRSUs, Exercisable at period end (in shares)	374,444
Market Performance Based Restricted Stock Units \| Stock Option Plan Amended Restated 2007 Equity Incentive Plan \| Executive Officer \| Cliff Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Unvested restricted stock units \| Stock Option Plan Amended Restated 2007 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs, period for recognition	3 years
Market performance-based restricted stock units granted (in shares)	1,522,000
MPRSUs granted, weighted average exercise price (in dollars per share) \| $ / shares	$ 16.77
RSUs vested and non-vested units expected to vest (in shares)	510,695
Unrecognized compensation cost \| $	$ 25.6
Unvested restricted stock units \| Stock Option Plan Amended Restated 2007 Equity Incentive Plan \| Contingent Consideration Liability Clinical Milestone
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market performance-based restricted stock units granted (in shares)	187,211
Award vesting period	3 years

Share based Compensation - Expense Summary (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity compensation expense	$ 6,341	$ 5,537	$ 13,819	$ 11,567
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity compensation expense	2,641	2,313	5,698	5,066
Selling, general and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity compensation expense	$ 3,700	$ 3,224	$ 8,121	$ 6,501

Assets and Liabilities Measured at Fair Value (Details) $ in Thousands	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Assets:
Fair value of assets	$ 482,158	$ 311,700
Liabilities:
Contingent consideration payable	26,800	25,400
Deferred compensation plan liability	2,731	2,258
Fair value of liabilities	29,531	27,658
T B200 Pompe Program \| Contingent Consideration Liability Clinical and Regulatory Milestones \| Callidus Biopharma Inc
Liabilities:
Contingent consideration payable	$ 26,300
T B200 Pompe Program \| Minimum \| Contingent Consideration Liability Clinical and Regulatory Milestones \| Callidus Biopharma Inc \| Probability of Milestone Achievement
Liabilities:
Discount rate (as a percent)	0.710
T B200 Pompe Program \| Maximum \| Contingent Consideration Liability Clinical and Regulatory Milestones \| Callidus Biopharma Inc \| Probability of Milestone Achievement
Liabilities:
Discount rate (as a percent)	1.000
Commercial paper
Assets:
Fair value of assets	$ 144,698	79,803
Asset-backed securities
Assets:
Fair value of assets	49,013	30,287
Corporate debt securities
Assets:
Fair value of assets	285,366	199,012
Money market
Assets:
Fair value of assets	3,081	2,598
Level 2
Assets:
Fair value of assets	482,158	311,700
Liabilities:
Contingent consideration payable	0	0
Deferred compensation plan liability	2,731	2,258
Fair value of liabilities	2,731	2,258
Convertible debt, fair value	666,200
Level 2 \| Commercial paper
Assets:
Fair value of assets	144,698	79,803
Level 2 \| Asset-backed securities
Assets:
Fair value of assets	49,013	30,287
Level 2 \| Corporate debt securities
Assets:
Fair value of assets	285,366	199,012
Level 2 \| Money market
Assets:
Fair value of assets	3,081	2,598
Level 3
Liabilities:
Contingent consideration payable	26,800	25,400
Deferred compensation plan liability	0	0
Fair value of liabilities	$ 26,800	$ 25,400
Level 3 \| T B200 Pompe Program \| Contingent Consideration Liability Clinical and Regulatory Milestones \| Probability Weighted Discounted Cash Flow \| Callidus Biopharma Inc \| Discount Rate
Liabilities:
Discount rate (as a percent)	0.110

Assets and Liabilities Measured at Fair Value - Level 3 Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of the period	$ 26,500	$ 274,300	$ 25,400	$ 269,722
Payment of contingent consideration in cash	0	(10,000)	0	(10,000)
Changes in fair value during the period, included in statement of operations	300	1,050	1,400	5,628
Balance, end of the period	$ 26,800	$ 265,350	$ 26,800	$ 265,350

Basic and Diluted Net Loss per Common Share (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net loss attributable to common stockholders	$ (61,833)	$ (48,136)	$ (111,751)	$ (103,129)
Denominator:
Weighted-average common shares outstanding - basic and diluted (in shares)	188,621,423	143,000,718	182,303,128	142,886,614
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			63,043,000	64,111,000
Options to purchase common stock
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			15,869,000	17,275,000
Convertible debt
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			40,850,000	40,850,000
Outstanding warrants, convertible to common stock
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			2,657,000	3,110,000
Unvested restricted stock units
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			3,556,000	2,826,000
Vested restricted stock units, unissued
Denominator:
Antidilutive securities excluded from computation of diluted earnings per share (in shares)			111,000	50,000