Aratana Therapeutics (PETX) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Entity Registrant Name	ARATANA THERAPEUTICS, INC.
Entity Central Index Key	1,509,190
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Trading Symbol	petx
Entity Common Stock, Shares Outstanding		46,844,907

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 66,427	$ 66,868
Short-term investments	498	747
Accounts receivable, net	2,438	2,406
Inventories	13,952	13,576
Prepaid expenses and other current assets	1,263	1,642
Total current assets	84,578	85,239
Property and equipment, net	1,047	1,166
Goodwill	41,683	41,295
Intangible assets, net	6,486	6,616
Restricted cash	350	350
Other long-term assets	528	526
Total assets	134,672	135,192
Current liabilities:
Accounts payable	1,929	7,451
Accrued expenses and other current liabilities	2,875	3,712
Licensing and collaboration commitment	200	7,000
Current portion – loans payable	20,083	17,333
Total current liabilities	25,087	35,496
Loans payable, net	13,882	19,492
Other long-term liabilities	67	70
Total liabilities	39,036	55,058
Commitments and contingencies (Notes 5 and 16)
Stockholders' equity:
Common stock, $0.001 par value; 100,000,000 shares authorized at March 31, 2018 and December 31, 2017, and 46,033,850 and 42,532,725 issued and outstanding at March 31, 2018 and December 31, 2017, respectively	46	43
Treasury stock, at cost; 89,604 and 80,916 shares at March 31, 2018 and December 31, 2017, respectively	(1,149)	(1,107)
Additional paid-in capital	338,483	321,599
Accumulated deficit	(235,064)	(233,316)
Accumulated other comprehensive loss	(6,680)	(7,085)
Total stockholders' equity	95,636	80,134
Total liabilities and stockholders' equity	$ 134,672	$ 135,192

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	46,033,850	42,532,725
Common stock, shares outstanding	46,033,850	42,532,725
Treasury stock, shares	89,604	80,916

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Total revenues	$ 4,043	$ 3,795
Costs and expenses
Cost of product sales	536	3,094
Royalty expense	806	323
Research and development	2,205	4,654
Selling, general and administrative	7,699	7,495
Amortization of intangible assets	130	64
In-process research and development	500
Total costs and expenses	11,876	15,630
Loss from operations	(7,833)	(11,835)
Other income (expense)
Interest income	141	85
Interest expense	(853)	(860)
Other expense, net	(3)	(2)
Total other expense	(715)	(777)
Net loss	$ (8,548)	$ (12,612)
Net loss per share, basic and diluted	$ (0.19)	$ (0.34)
Weighted average shares outstanding, basic and diluted	44,788,068	36,711,601
Licensing and Collaboration [Member]
Revenues
Total revenues	$ 1,706	$ 903
Product Sales [Member]
Revenues
Total revenues	$ 2,337	$ 2,892

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Statements Of Comprehensive Loss [Abstract]
Net loss	$ (8,548)	$ (12,612)
Other comprehensive income:
Foreign currency translation adjustment	405	299
Other comprehensive income	405	299
Comprehensive loss	$ (8,143)	$ (12,313)

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net loss	$ (8,548)	$ (12,612)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,384	1,814
Depreciation and amortization expense	249	392
Non-cash interest expense	140	119
Changes in operating assets and liabilities:
Accounts receivable, net	(32)	(3,452)
Inventories	(376)	2,075
Prepaid expenses and other current assets	360	706
Other assets	10	33
Accounts payable	(5,561)	(6,222)
Accrued expenses and other liabilities	(840)	(1,289)
Net cash used in operating activities	(13,214)	(18,436)
Cash flows from investing activities
Milestone payments for intangible assets		(3,000)
Purchase of investments	(498)	(494)
Proceeds from maturities and sales of investments	747	996
Net cash provided by (used in) investing activities	249	(2,498)
Cash flows from financing activities
Taxes paid for awards vested under equity incentive plans	(42)	(11)
Proceeds from stock option exercises	5	6
Proceeds from issuance of common stock, net of commission	15,614	1,223
Payments for common stock issuance costs	(57)	(67)
Payments on loans payable	(3,000)
Net cash provided by financing activities	12,520	1,151
Effect of exchange rate on cash	4	5
Net decrease in cash, cash equivalents and restricted cash	(441)	(19,778)
Cash, cash equivalents and restricted cash, beginning of period	67,218	87,657
Cash, cash equivalents and restricted cash, end of period	66,777	67,879
Supplemental disclosure of cash flow information:
Cash paid for interest	728	$ 733
Supplemental disclosure of noncash investing and financing activities:
Unpaid common stock issuance costs included in accounts payable	$ 38

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Business Overview Aratana Therapeutics, Inc., including its subsidiaries (the “Company” or “Aratana”) was incorporated on December 1, 2010 under the laws of the State of Delaware. T he Company is a pet therapeutics company focused on licensing, developing and commercializing innovative therapeutics for dogs and cats. The Company has one operating segment: pet therapeutics. Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements of the Company for the year ended December 31, 2017 and the notes thereto in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 14, 2018 (“2017 Annual Report”) . In the opinion of management, all adjustments, consisting of a normal and recurring nature, considered necessary for a fair presentation, have been included. The Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit of $235,064 as of March 31, 2018 . The Company expects to continue to generate operating losses for the foreseeable future. The Company believes that its cash, cash equivalents and short-term investments at March 31, 2018, will be sufficient to fund operations and debt obligations at least through June 30, 2019. As disclosed in Note 8 to the consolidated financial statements, the Company has a term loan and a revolving credit facility with an aggregate principal balance of $33,500 as of March 31, 2018. The loan agreement requires that the Company maintain certain minimum liquidity at all times (the greater of cash equal to fifty percent ( 50% ) of outstanding balance or remaining months’ liquidity, which is calculated on an average trailing three (3) month basis, equal to six (6) months or greater) , which as of March 31, 2018, was approximately $26,950 . If the minimum liquidity covenant is not met, the Company may be required to repay the loans prior to their scheduled maturity dates. At March 31, 2018, the Company was in compliance with all financial covenants. The Company expects an increase in its investment related to commercial activities, including procuring of inventories needed to supply the marketplace, investing to further support adoption and awareness of the Company’s marketed products and payment of milestones related to approval and commencement of commercial sales. This will impact the minimum liquidity that needs to be maintained under the loan agreement. As a result, the Company will need additional capital to fund its operations and debt obligations beyond June 30, 2019, which the Company may obtain from corporate collaborations and licensing arrangements, or other sources, such as public or private equity offerings and further debt (re)financings. The future viability of the Company beyond June 30, 2019, is dependent on its ability to raise additional capital to finance its operations, to fund on-going research and development costs, commercialization of its therapeutics and therapeutic candidates and to satisfy debt covenants. If the Company is not able to raise additional capital on terms acceptable to it, or at all, as and when needed, the Company would be forced to delay, reduce, or eliminate certain research and development programs, reduce or eliminate discretionary operating expenses or grant rights to develop and market therapeutics or therapeutic candidates that it would otherwise prefer to develop and market itself, which could otherwise adversely affect its business prospects. The Company’s failure to raise capital, as and when needed, would have a negative impact on its financial condition and its ability to pursue its business strategies as this capital is necessary for it to perform the research and development and commercial activities required to generate future revenue streams. Consolidation The Company’s consolidated financial statements include its financial statements and those of its wholly-owned subsidiaries . Intercompany balances and transactions are eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from those estimates. Revenue from Contracts with Customers Effective January 1, 2018, the Company adopted ASC 606 “Revenue from Contracts with Customers” (“ASC 606”) using the modified retrospective transition method. Prior to January 1, 2018, the Company recognized revenue using the guidance of ASC 605 “Revenue Recognition” (“ASC 605”). The Company recognizes revenue when its customer obtains control of the promised goods or services, in an amount that reflects the consideration which the Company expects to be entitled to in exchange for those goods or services. The Company determines revenue recognition from contracts with customers as follows: · identify the contract(s); · identify the performance obligations in the contract(s); · determine the transaction price; · allocate the transaction price to the performance obligations in the contract; and · recognize revenue wh en (or as) the Company satisfies a performance obligation. The Company’s principal revenue streams and their respective accounting treatments are discussed below and further in Note 2, “Revenue” :  (i) Product Sales, Net The Company sells its products to its customers who could either be the end users (such as veterinarians, clinics, or animal hospitals) of the product or distributors who subsequently resell the Company’s products to end users. Revenues from product sales are recognized when the customer obtains control of the Company’s product, which occurs at a point in time, upon delivery to the customer. The Company’s delivery of its products to customers constitutes a single performance obligation as there are no other promises to deliver goods or services beyond what is specified in each accepted customer order. Product sales are recorded net of applicable reserves for variable consideration, including product returns, allowances, discounts, and rebates . Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established. Components of variable consideration include product returns, allowances, discounts, and rebates. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable (generally, for credits that the Company issues for free goods provided by distributors to end customers in conjunction with promotional programs) or a current liability (generally, reserves for products that remained in the distribution channel inventories at each reporting period end that the Company expects the distributors will provide to end customers free of charge in conjunction with promotional programs). These estimates take into consideration a range of possible outcomes for the expected value (probability-weighted estimate) or relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the respective underlying contracts. The amount of variable consideration which is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Product Returns Consistent with the industry practice, the Company generally offers customers a limited right of return of damaged or expired product that has been purchased from the Company or the Company’s distributors in exchange for an unexpired product. Exchanges due to expiry are typically allowed for a period of six months after the product’s expiration date. The Company estimates the amount of its product sales that may be returned by its customers and records these estimates as a reduction of product revenues in the period the related product revenues are recognized, as well as within accrued expenses and other current liabilities, net in the consolidated balances sheets. The Company currently estimates product return liabilities using available industry data, its own sales data and data provided by the Company’s distributors such as the inventories remaining in the distribution channel. The Company has received an immaterial amount of returns to date and believes that returns of its products in future periods will be minimal. The Company does not record a return asset associated with the returned damaged or expired goods due to such asset is deemed to be fully impaired at the time of product return. Sales Discounts and Allowances The Company compensates its distributors for sales order management, data and distribution and other services through sales discounts and allowances. However, such services are not distinct from the Company’s sale of products to distributors and, therefore, these discounts and allowances are recorded as a reduction of revenue in the statements of operations, as well as a reduction to accounts receivable, net in the consolidated balance sheets.  (ii) Licensing and Collaboration Revenues Revenues derived from product out-licensing arrangements typically consist of an initial non-refundable, up-front payment at inception of the license, subsequent milestone payments contingent on the achievement of certain regulatory, development and commercial milestones, and royalties on the net sales of the Company’s products. Licenses of Intellectual Property If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the contract, the Company recognizes revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company will evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestones Revenues from achievement of milestones generally represent a form of variable consideration as the payments are likely to be contingent on the occurrence of future events. The Company estimates milestones probable to be achieved and includes in the transaction price based on either the expected value (probability-weighted estimate) or most likely amount approach. The most likely amount is used by the Company for milestone payments with a binary outcome (i.e., the Company receives all or none of the milestone payment). Milestone payments that are not within the control of the Company or the customer, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The estimated milestone-related variable consideration is only recognized as revenue when the related performance obligation is satisfied and the Company determines that it is probable that there will not be a significant reversal of cumulative revenue recognized in future periods (i.e. variable consideration constraint). At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect licensing and collaboration revenues and earnings in the period of adjustment. For milestones not able to overcome the variable consideration constraint, not considered probable or that are determined to be sales-or usage royalties, as described later, the Company recognizes revenue when the milestones are achieved. Sales-Based Royalty Revenue The Company’s sales-based royalty revenue could consist of sales-based milestones or percentage of net sales royalties. The Company recognizes sales-based royalties related to the Company’s out-licensed intellectual property when (or as) the later of the following events occurs:  · the sale occurs; or · the performance obligation to which some or all of the sales-based or usage-based royalty has been allocated has been satisfied (or partially satisfied).  Sales-based royalties revenues recorded by the Company are based on the licensee’s or sub-licensee’s sales that occurred during the relevant period. Differences between actual and estimated royalty revenues are adjusted in the period in which they become known, typically in the following quarter. If the Company is unable to reasonably estimate royalty revenue or does not have access to the information, then the Company records royalty revenue when the information needed for a reliable estimate becomes available. Royalty revenue is included in licensing and collaboration revenue in the consolidated statements of operations. The Company recognizes revenue from sales-based milestones when the milestones are achieved. Property and Equipment, Net Property and equipment is recorded at historical cost, net of accumulated depreciation and amortization of $1,310 and $1,188 , as of March 31, 2018 and December 31, 2017 , respectively. New Accounting Standards Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (“FASB”) issued guidance on recognizing revenue in contracts with customers. The guidance affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (e.g., insurance contracts or lease contracts). This guidance superseded the revenue recognition requirements in topic, Revenue Recognition , and most industry-specific guidance. The core principle of the guidance is that an entity should 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. The Company adopted this guidance on January 1, 2018. The impact of adoption is described further in Note 2 , “Revenue.” Leases In February 2016, the FASB issued guidance that requires, for operating leases, a lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted and is to be applied on a modified retrospective transition. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. The Company currently expects that its operating lease commitments will be subject to the new guidance which will result in recognition of operating lease liabilities and right-of-use assets in the consolidated balance sheets upon the adoption of the new guidance. However, the Company’s assessment of the impact of adoption is still ongoing. Compensation – Stock Compensation In May 2017, the FASB issued guidance on determining which changes to the terms or conditions of share-based payment awards require an entity to apply modification accounting. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted this guidance on January 1, 2018, and the adoption did not have a material impact on its consolidated financial statements.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue [Abstract]
Revenue	2. Revenue Adoption of ASC 606 On January 1, 2018, the Company adopted ASC 606 using the modified retrospective method applied to those contracts that were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with the Company’s historic accounting under ASC 605. The Company recorded a net reduction of $6,800 , net of $0 tax , to the opening balance of accumulated deficit within stockholders’ equity , and a corresponding reduction to licensing and collaboration commitment as of January 1, 2018, due to the cumulative impact of adopting ASC 606, with the impact solely related to the Company’s variable consideration within its licensing and collaboration agreement with Elanco Animal Health, Inc., a division of Eli Lilly & Co. (“Elanco”) . Under previous guidance of ASC 605, this commitment was fully deferred and recognized as a liability until such time as payments under the obligation were made, or any unpaid portion would have been recognized as revenue when the commitment expired on December 31, 2018. Under ASC 606, this obligation is accounted for as variable consideration. The Company records a contract liability based on the amount of the obligation that it expects to pay which was $200 as of March 31, 2018. This amount was determined based on management estimates, which included consideration of Elanco’s development plan. Since inception of the arrangement, no amounts had been paid out or submitted to the Company for reimbursement. Had the Company still applied ASC 605 for the three months ended March 31, 2018, revenues would have been the same as compared to ASC 606. Disaggregated Revenues The following table presents the Company’s revenues disaggregated by revenue source. All product sales are derived from United State sources and sales taxes are excluded from revenues.     Three Months Ended  March 31,  2018 2017 (1)  Revenues  Licensing and collaboration revenue  GALLIPRANT $ 1,706 $ 903  Total licensing and collaboration revenue 1,706 903  Product sales  NOCITA $ 1,547 $ 327  ENTYCE 790 —  GALLIPRANT — 2,545  Other — 20  Total product sales 2,337 2,892  Total revenues $ 4,043 $ 3,795 (1) Prior period amounts have not been adjusted under the modified retrospective method Product Sales The Company generates product sales revenues primarily by selling its marketed therapeutics directly to end users (such as veterinarians, clinics, or animal hospitals) and distributors. Direct to end user sales revenues consist primarily of NOCITA, and distributor product sales revenues consist primarily of ENTYCE. As of March 31, 2018 and December 31, 2017, respectively, reserves for product returns and allowances related to NOCITA and ENTYCE were $145 and $114 . Licensing and Collaboration Revenue The Company generate s licensing and collaboration revenue solely from the Elanco Collaboration, License, Development and Commercialization Agreement (as amended, the “Collaboration Agreement”) and Co-Promotion agreement (“the Co-Promotion Agreement”) (collectively, “the Elanco Agreements”) as follows: · sales-based royalties from the Elanco Agreements consisting of a percentage of net sales of GALLIPRANT by Elanco that are recognized as revenue as the underlying sales of GALLIPRANT are made by Elanco; · sales-based royalties from the Collaboration Agreement consisting of sales-based milestones of GALLIPRANT by Elanco that are recognized as revenue if and when the sales threshold is achieved by Elanco; · regulatory milestones from the Collaboration Agreement that are recognized as revenue if and when achieved; and · variable consideration related to the Collaboration Agreement licensing and collaboration commitment (contract liability) that is recognized as revenue when it is not subject to variable consideration constraint. Reconciliation of Contract Balances The change in contract liability balances for the three months ended March 31, 2018, was as follows: Licensing and Collaboration Commitment    2018  As of January 1, $ 7,000  ASC 606 adoption (6,800)  Revenue recognized —  As of the end of period, $ 200  The Company recorded a net reduction of $6,800 , net of $0 tax , to the opening balance of accumulated deficit within stockholders' equity as of January 1, 2018, due to the cumulative impact of adopting ASC 606. The Company reviewed the current facts and circumstances and concluded that no changes to the previously estimated transaction price for the Collaboration Agreement at March 31, 2018, are required, and therefore, no change in variable consideration was recognized as revenue for the three months ended March 31, 2018. Unsatisfied Performance Obligations As of the adoption date of ASC 606 and March 31, 2018, the Company had no unsatisfied performance obligations. Significant Judgements The Company’s significant judgements relate to the updating of the transaction price and variable consideration of the Collaboration Agreement. The Company used current facts and circumstances to calculate the updated transaction price using the expected value (probability weighted estimate). Facts and circumstances considered included the current Elanco development plan for GALLIPRANT. Practical Expedients and Exemptions The Company has deemed that there is no significant financing component present in the agreements with the Company’s customers as trade payment terms with its customers do not exceed one year. The Company expenses sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within selling, general and administrative expenses. 

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
	Mar. 31, 2018
Fair Value of Financial Assets and Liabilities [Abstract]
Fair Value of Financial Assets and Liabilities	3. Fair Value of Financial Assets and Liabilities Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis The carrying values and estimated fair values of the Company’s financial assets which are measured at fair value on a recurring basis were as follows:      Fair Value Measurements as of  Carrying March 31, 2018 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,462 $ — $ 9,462 $ — $ 9,462  Short-term investments:  Short-term marketable securities - certificates of deposit 498 — 498 — 498  $ 9,960 $ — $ 9,960 $ — $ 9,960      Fair Value Measurements as of  Carrying December 31, 2017 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 8,964 $ — $ 8,964 $ — $ 8,964  Short-term investments:  Short-term marketable securities - certificates of deposit 747 — 747 — 747  $ 9,711 $ — $ 9,711 $ — $ 9,711 The financial assets above are measured at fair value using quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3). Certain estimates and judgments are required to develop the fair value amounts shown above. The fair value amounts shown above are not necessarily indicative of the amounts that the Company would realize upon disposition, nor do they indicate the Company’s intent or ability to dispose of the financial instrument. The following methods and assumptions were used to estimate the fair value of each material class of financial instrument: · Cash equivalents – the fair value of the cash equivalents has been determined to be amortized cost given the short duration of the securities. · Marketable securities (short-term) – the fair value of marketable securities has been determined to be amortized cost given the short duration of the securities. The Company had no financial liabilities measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017. Financial Assets and Liabilities that are not Measured at Fair Value on a Recurring Basis The carrying values and estimated fair value s of the Company’s financial liabilities which are not measured at fair value on a recurring basis were as follows:      March 31, 2018  Carrying Value Fair Value  Liabilities:  Loans payable (Level 2) $ 33,965 $ 33,807      December 31, 2017  Carrying Value Fair Value  Liabilities:  Loans payable (Level 2) $ 36,825 $ 36,973 Loans payable values above include both the current and the long-term loans balances as of March 31, 2018 and December 31, 2017. The financial liabilities above are measured at fair value using quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3). Certain estimates and judgments were required to develop the fair value amounts. The fair value amount shown above is not necessarily indicative of the amounts that the Company would realize upon disposition, nor does it indicate the Company’s intent or ability to dispose of the financial instrument. The fair value of loans payable was estimated using discounted cash flow analysis discounted at current rates. The Company had no financial assets not measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017.

Investments

Investments	3 Months Ended
	Mar. 31, 2018
Investments [Abstract]
Investments	4. Investments Marketable Securities Marketable securities consisted of the following:     March 31, 2018  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 498 $ — $ — $ 498  Total $ 498 $ — $ — $ 498      December 31, 2017  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 747 $ — $ — $ 747  Total $ 747 $ — $ — $ 747 At March 31, 2018 and December 31, 2017 , short-term marketable securities consisted of investments that mature within one year. Short-term marketable securities are recorded as short-term investments in the consolidated balance sheets.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2018
Inventories [Abstract]
Inventories	5. Inventories Inventories are stated at the lower of cost and net realizable value and consisted of the following:      March 31, 2018 December 31, 2017  Raw materials $ 627 $ 1,132  Work-in-process 11,033 12,322  Finished goods 2,292 122  $ 13,952 $ 13,576 As of March 31, 2018 and December 31, 2017, the Company had non-cancellable open orders for the purchase of inventories of approximately $2,687 , which is expected to be paid in the next 12 months, and $7,132 , respectively. As of December 31, 2017, raw materials included $777 of GALLIPRANT inventories. As part of the manufacturing transfer of GALLIPRANT (Note 10), the Company transferred these raw materials to Elanco, and was reimbursed for the raw materials by Elanco during the three months ended March 31, 2018.

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
Goodwill	6. Goodwill Goodwill is recorded as an indefinite-lived asset and is not amortized for financial reporting purposes but is tested for impairment on an annual basis or when indications of impairment exist. No goodwill impairment losses have been recognized to date. Goodwill is not expected to be deductible for income tax purposes. The Company performs its annual impairment test of the carrying value of the Company’s goodwill during the third quarter of each year. Goodwill as of March 31, 2018 , was as follows:      Gross Impairment Net  Carrying Value Losses Carrying Value  Goodwill $ 41,683 $ — $ 41,683  The change in the net book value of goodwill for the three months ended March 31, 2018 , was as follows:     2018  As of January 1, $ 41,295  Effect of foreign currency exchange 388  As of the end of the period, $ 41,683  

Intangible Assets, Net

Intangible Assets, Net	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
Intangible Assets, Net	7. Intangible Assets, Net The change in the net book value of intangible assets for the three months ended March 31, 2018 , was as follows:      2018  As of January 1, $ 6,616  Amortization expense (130)  As of the end of the period, $ 6,486 The Company recognized amortization expense of $1 30 and $64 for the three months ended March 31, 2018 and 2017, respectively. Amortized Intangible Assets Amortized intangible assets as of March 31, 2018 , were as follows (excluding intellectual property rights for formerly marketed products that were fully impaired in prior periods):     Gross Net Weighted  Carrying Accumulated Carrying Average  Value Amortization Value Useful Life  Intellectual property rights for currently marketed products $ 7,000 $ 514 $ 6,486 14.1 Years  Amortized intangible assets as of December 31, 2017, were as follows:    Gross Net Weighted  Carrying Accumulated Carrying Average  Value Amortization Value Useful Life  Intellectual property rights for currently marketed products $ 7,000 $ 384 $ 6,616 14.1 Years  Intellectual property rights for formerly marketed products 38,652 38,652 — N/A  $ 45,652 $ 39,036 $ 6,616 Unfavorable outcomes of the Company’s development activities or the Company’s estimates of the market opportunities for the therapeutic candidates could result in additional impairment charges in future periods. Intellectual Property Rights for Currently Marketed Products As of March 31, 2018 and December 31, 2017, intellectual property rights for currently marketed products relate to intangible assets capitalized for NOCITA, GALLIPRANT and ENTYCE in conjunction with approval/post-approval milestone payments made under the Company's licensing agreements.

Debt

Debt	3 Months Ended
	Mar. 31, 2018
Debt [Abstract]
Debt	8. Debt Loan and Security Agreements Effective as of October 16, 2015, the Company and its wholly-owned subsidiary Vet Therapeutics, Inc. (the “Borrowers”), entered into a Loan and Security Agreement (“Loan Agreement”), with Pacific Western Bank, or Pacific Western, as a collatera l agent and Oxford Finance, LLC (collectively, the “Lenders”), pursuant to which the Lenders agreed to make available to the Company a term loan in an aggregate principal amount up to $35,000 and a revolving credit facility in an aggregate principal amount up to $5,000 subject to certain conditions to funding. The term loan and the revolving credit facility are secured by all of the Borrowers’ personal property other than intellectual property and certain other customary exclusions. Subject to customary exceptions, the Company is not permitted to encumber its intellectual property. The outstanding principal balance under the Loan Agreement was $28,500 under the term loan facility and $5,000 under the revolving credit facility at March 31, 2018 . D uring the three months ended March 31, 2018 and 2017, the Company recognized interest expense of $853 and $860 , respectively. Amortization of debt issuance costs, recognized as interest expense, was $140 and $119 for the three months ended March 31, 2018 and 2017, respectively. The Company was required to make interest-only payments on the revolving credit facility until October 16, 2017, when all principal and accrued interest were due. Effective as of July 31, 2017, the Borrowers and Lenders entered into a second amendment to the Loan Agreement (the “Second Amendment”). The terms of the Second Amendment, among other things, extend the maturity date of the existing revolving credit facility to October 16, 2019 (the “Revolving Line Maturity Date”), with amortized equal repayments of the principal outstanding under the revolving credit facility beginning November 1, 2018, and provide a six -month interest only period for the term loans, starting on the date of the Second Amendment. The Company is not subject to any new financial covenants as a result of the Second Amendment. At the closing of the Second Amendment, the Company paid the Lenders an amendment fee of $150 and a facility fee of $60 . The Company is also obligated to pay a new termination fee equal to $165 upon the earliest to occur of the Revolving Line Maturity Date, the acceleration of the revolving credit facility or the termination of the revolving credit facility. The existing termination fee of $165 was due upon the original revolving maturity date, October 16, 2017 , and was paid on October 17, 2017 . The term loan and the revolving credit facility bear interest per annum at the greater of (i) 6.91% or (ii) 3.66% plus the prime rate, which is customarily defined. As of March 31, 2018 , interest rate for the term loan and the revolving credit facility was 8.41% . In addition, the Company is obligated to pay a final payment fee equal to 3.30% of the principal amount of such term loan, if the term loan is being prepaid or repaid with respect to the term loan upon the earliest to occur of October 16, 2019, the acceleration of any term loan or the prepayment of a term loan. The Company will also be obligated to pay an unused-line fee equal to 0.25% per annum of the average unused portion of the revolving credit facility. The Loan Agreement contains customary representations and warranties and customary affirmative and negative covenants, including, among others, limits or restrictions on the Borrowers’ ability to incur liens, incur indebtedness, make certain restricted payments, make certain investments, merge, consolidate, make an acquisition, enter into certain licensing arrangements and dispose of certain assets. In addition, the Loan Agreement contains customary events of default that entitle the Lenders to cause the Borrowers’ indebtedness under the Loan Agreement to become immediately due and payable. The events of default, some of which are subject to cure periods, include, among others, a non-payment default, a covenant default, the occurrence of a material adverse change in the Company’s business, the occurrence of an insolvency, a material judgment default, defaults regarding other indebtedness and certain actions by governmental authorities. Upon the occurrence and for the duration of an event of default, an additional default interest rate equal to 4% per annum will apply to all obligations owed under the Loan Agreement. The Loan Agreement requires that the Company maintain certain minimum liquidity at all times (the greater of cash equal to fifty percent ( 50% ) of outstanding credit extensions or remaining months’ liquidity, which is calculated on an average trailing three (3) month basis, equal to six (6) months or greater) , which as of March 31, 2018 , was approximately $ 26,950 . If the minimum liquidity covenant is not met, the Company may be required to repay the term loan and the revolving credit facility prior to their scheduled maturity dates. At March 31, 2018 , the Company was in compliance with all financial covenants. The Company’s loans payable balance as of March 31, 2018 , was as follows:   Principal amounts  Term loan, 8.41% , principal payments from February 1, 2018 through October 1, 2019 $ 28,500  Revolving credit facility, 8.41% , principal payments from November 1, 2018 through October 1, 2019 5,000  Add: accretion of final payment and termination fees 748  Less: unamortized debt issuance costs (283)  As of the end of the period $ 33,965 As of March 31, 2018 , $ 18,000 and $2,083 related to the term loan and the revolving credit facility, respectively, were classified as current portion – loans payable.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2018
Accrued Expenses and Other Current Liabilities [Abstract]
Accrued Expenses and Other Current Liabilities	9. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following:     March 31, 2018 December 31, 2017  Payroll and related expenses $ 1,126 $ 2,314  Professional fees 206 208  Royalty expense 806 718  Interest expense 235 249  Research and development costs 57 5  Other 445 218  Total $ 2,875 $ 3,712 

Agreements

Agreements	3 Months Ended
	Mar. 31, 2018
Agreements [Abstract]
Agreements	10. Agreements RaQualia Pharma Inc. (“RaQualia”) On December 27, 2010, the Company entered into two Exclusive License Agreements with RaQualia (as amended, the “RaQualia Agreements”) that granted the Company global rights, subject to certain exceptions for injectables in Japan, Korea, China and Taiwan for development and commercialization of licensed animal health products for compounds RQ-00000005 (ENTYCE ® , also known as AT-002) and RQ-00000007 (GALLIPRANT ® , also known as AT-001). The Company will be required to pay RaQualia remaining milestone payments associated with GALLIPRANT and ENTYCE of up to $4,000 and $3,000 , respectively, upon the Company’s achievement of certain development, regulatory and commercial milestones, as well as mid-single digit royalties on the Company’s or the Company’s sublicensee’s product sales. As of March 31, 2018 , the Company had paid $11,500 in milestone payments since execution of the RaQualia Agreements , and no milestone payments were accrued . No milestones were achieved during the three months ended March 31, 2018. It is possible that a milestone related to the RaQualia Agreements will be achieved within the next twelve months totaling $2,000 . Elanco GALLIPRANT On April 22, 2016, the Company entered into the Collaboration Agreement pursuant to which the Company granted Elanco rights to develop, manufacture, market and commercialize the Company’s products based on licensed grapiprant rights and technology , including GALLIPRANT (collectively, “Grapiprant Products”) . Pursuant to the Collaboration Agreement, Elanco will have exclusive rights globally outside the United States and co-promotion rights with the Company in the United States during the term of the Collaboration Agreement. Under the terms of the Collaboration Agreement, the Company received a non-refundable, non-creditable upfront payment of $45,000 . The Company is entitled to a $4,000 milestone payment upon European approval of a Grapiprant Product for the treatment of pain and inflammation, another $4,000 payment upon achievement of a development milestone related to the manufacturing of a Grapiprant Product from an alternate supply source, and payments up to $75,000 upon the achievement of certain sales milestones. The sales milestone payments are subject to a one -third reduction for each year the occurrence of the milestone is not achieved beyond December 31, 2021, with any non-occurrence beyond December 31, 2023, cancelling out the applicable milestone payment obligation entirely. The Collaboration Agreement also provides that Elanco will pay the Company royalty payments on a percentage of net sales in the mid-single to low-double digits. The Company was responsible for all development activities required to obtain the first registration or regulatory approval for a Grapiprant Product for use in dogs in each of the European Union (“the EU Product Registration”) and the United States, and Elanco is responsible for all other development activities. First registration for a Grapiprant Product in the United States was achieved before the completion of the Collaboration Agreement and EU Product Registration was achieved in January 2018. In addition, the Company and Elanco have agreed to pay 25% and 75% , respectively, of all third-party development fees and expenses through December 31, 2018, in connection with preclinical and clinical trials necessary for any additional registration or regulatory approval of Grapiprant Products, provided that the Company’s contribution to such development fees and expenses is capped at $7,000 , which was recorded as licensing and collaboration commitment liability in the consolidated balance sheets at December 31, 2017. Upon adoption of ASC 606 (Note 2), the Company relieved $6,800 of its licensing and collaboration commitment liability leaving a balance of $200 as of March 31, 2018. The licensing and collaboration commitment liability balance in future periods will be updated at each future reporting date to reflect current facts and circumstances. Any remaining balance will be recognized as licensing and collaboration revenue on December 31, 2018, when the Company’s obligation to fund 25% of Elanco’s development efforts expires. Commencing on the effective date of the Collaboration Agreement, the Company was responsible for the manufacture and supply of all of Elanco’s reasonable requirements of active pharmaceutical ingredient (“API”) and/or finished Grapiprant Products under the supply terms agreed upon pursuant to the Collaboration Agreement. However, Elanco retained the ability to assume all or a portion of the manufacturing responsibility during the term of the Collaboration Agreement. On April 28, 2017, the Company and Elanco entered into an amendment (the “Amendment”) to the Collaboration Agreement. Under the Amendment, Elanco agreed to submit binding purchase orders to the Company, within 15 days of the effective date of the Amendment, for certain finished Grapiprant Products to be produced from certain batches of API the Company agreed to purchase from its third-party manufacturer (the “API Batches”). In addition, Elanco agreed to pay the Company for the API Batches within 30 days after the Company provides Elanco with proof of payment to the manufacturer for such API Batches. The Amendment provides that, in the event Elanco provided notice of its intent to assume responsibility for manufacturing, Elanco would assume all responsibilities of the Company with respect to any undelivered API, including paying the third-party manufacturer for such undelivered API. In July 2017, pursuant to Sections 8.2.2 and 10.1(c) of the Collaboration Agreement, as amended, Elanco provided the Company notice of its intent to assume responsibility for manufacturing of the Grapiprant Products and its intent to assume the applicable regulatory approvals. In September 2017, the Company and Elanco finalized the transfer of the applicable regulatory approvals in the United States and the responsibility for manufacturing of Grapiprant Products to Elanco. In connection with this assumption of manufacturing responsibility, Elanco compensated the Company $10,832 for certain Grapiprant Product inventories and manufacturing considerations. As of March 31, 2018, the Company had not earned any milestone payments since execution of the Collaboration Agreement, and no milestone payments were accrued. The Company will recognize revenue from the milestones if and when they are achieved by Elanco. On April 22, 2016, in connection with the Collaboration Agreement, the Company entered into the Co-Promotion Agreement to co-promote Grapiprant Products in the United States. Under the terms of the Co-Promotion Agreement, Elanco has agreed to pay the Company, as a fee for promotional services performed and expenses incurred by the Company under the Co-Promotion Agreement, (i) 25% of the gross margin on net sales of Grapiprant Product sold in the United States under the Collaboration Agreement prior to December 31, 2018 (unless extended by mutual agreement), and (ii) a mid-single digit percentage of net sales of the Grapiprant Product in the United States after December 31, 2018 through 2028 (unless extended by mutual agreement). VetStem BioPharma, Inc. (“VetStem”) On June 12, 2014, the Company entered into an Exclusive License Agreement with VetStem (as amended, the “VetStem Agreement”) that granted the Company the exclusive United States rights for commercialization and development of VetStem’s allogeneic stem cells being developed for the treatment of pain and inflammation of canine osteoarthritis (“AT-016”). In January 2018, the Company exercised its right to terminate the VetStem Agreement, and on April 19, 2018, the termination became effective. During the three months ended March 31, 2018, the Company did not incur any development expenses or milestones . As a result of the termination of the VetStem Agreement, the Company does not anticipate having to reimburse any further development expenses or make milestone payments to VetStem. AskAt Inc. (“AskAt”) AT-019 On February 28, 2018, the Company entered into an Exclusive License Agreement with AskAt (the “AskAt Agreement”) that granted the Company an exclusive global license for development and commercialization of compound AT-019 in the field of animal health. Under the terms of the AskAt Agreement, the Company paid an initial upfront license fee of $500 in the second quarter of 2018. The AskAt Agreement was accounted for as an asset acquisition. On the date of acquisition, the licensed technology had not reached technological feasibility in animal health indications and had no alternative future use in the field of animal health. Accordingly, in-process research and development expense of $500 was recorded upon acquisition in the first quarter of 2018. As of March 31, 2018, the initial upfront license fee was included in the accounts payable in the consolidated balance sheets. The Company will be required to pay remaining milestone payments of up to $15,500 upon the Company’s achievement of $3,000 of certain development/regulatory and $12,500 of commercial milestones, as well as tiered single digit royalties on the Company’s product sales, if any. The commercial milestones owed to AskAt under the AskAt Agreement begin to be triggered upon the first commercial sale with the final tier being owed to AskAt once annual net sales reach $100,000 . Milestones, at the discretion of the Company, can be paid 50% in cash and 50% in a number of the Company’s shares as determined per the terms of the AskAt Agreement. As of March 31, 2018, the Company had not accrued or paid any milestone or royalty payments since execution of the AskAt Agreement. The Company does not expect to achieve any milestones related to the AskAt Agreement in the next twelve months. Collaboration and Option Agreement On February 28, 2018, in connection with the AskAt Agreement, the Company entered into Collaboration and Option Agreement (the “COA”) with AskAt for animal health research, including a right of first negotiation agreement for multiple therapeutic candidates with potential in pain, allergy and cancer. During the three months ended March 31, 2018, the Company paid an initial upfront option fee of $500 under the terms of the COA, which was recognized as research and development expense in the consolidated statements of operations.

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2018
Common Stock [Abstract]
Common Stock	11. Common Stock Authorized Common Stock As of March 31, 2018 and December 31, 2017, the authorized number of shares of common stock was 100,000,000 , par value $0.001 per share. Common Stock Outstanding As of March 31, 2018 , and December 31, 2017 there were 46,033,850 and 42,532,725 shares of the Company’s common stock outstanding, net of 809,684 and 491,861 shares of unvested restricted common stock, respectively. Treasury Stock As of March 31, 2018 and December 31, 2017, there were 89,604 and 80,916 shares of the Company’s common stock held as treasury stock at a cost of $1,149 and $1,107 , respectively. During the three months ended March 31, 2018 and 2017, 8,688 and 1,342 shares of restricted stock at a cost of $4.90 and $7.88 per share, respectively , were withheld to satisfy employee tax withholding obligations arising in conjunction with the vesting of restricted stock pursuant to the Company’s 2013 Incentive Award Plan (the “2013 Plan”). Shelf Registration Statement On August 4, 2017, the Company filed a shelf registration statement on Form S-3 (Reg. No. 333-219681) (the “Shelf Registration Statement”) with the SEC. The Shelf Registration Statement was declared effective by the SEC on August 16, 2017. The Shelf Registration Statement allows the Company to offer and sell, from time to time, up to $100,000 of common stock, preferred stock, debt securities, warrants, units or any combination of the foregoing in one or more future public offerings. The terms of any future offering would be determined at the time of the offering and would be subject to market conditions and approval by the Company’s Board of Directors. Any offering of securities covered by the Shelf Registration Statement will be made only by means of a written prospectus and prospectus supplement authorized and filed by the Company. At-the-Market Offering Cowen and Company, LLC On December 18, 2017, the Company entered into a Sales Agreement (“Cowen Sales Agreement”) with Cowen and Company, LLC (“Cowen”) pursuant to which the Company may sell from time to time, at its option, up to an aggregate of $50,000 of shares of its common stock through Cowen, as sales agent. Any sales of the shares of common stock would be made under the Company’s effective Registration Statement on Form S-3 (Reg. No. 333-219681), by means of ordinary brokers’ transactions on the Nasdaq Global Market or otherwise. Additionally, under the terms of the Cowen Sales Agreement, the shares of common stock may be sold at market prices, at negotiated prices or at prices related to the prevailing market price. The Company has agreed to pay Cowen a commission of 3% of the gross proceeds from the sale of such shares of common stock. During the three months ended March 31, 2018, the Company sold 3,383,963 shares of common stock for aggregate net proceeds of $15,498 , after deducting commission fees of $483 and issuance costs of $117 . As of the date of this filing, approximately $33,900 of shares of common stock remained available for sale under the Cowen Sales Agreement.

Stock-Based Awards

Stock-Based Awards	3 Months Ended
	Mar. 31, 2018
Stock-Based Awards [Abstract]
Stock-Based Awards	12. Stock-Based Awards 2010 Equity Incentive Plan Activity related to stock options under the 2010 Equity Incentive Plan (the “2010 Plan”) for the three months ended March 31, 2018 , was as follows:     Weigh t ed  Shares Weighted Average  Issuable Average Remaining Aggregate  Under Exercise Contractual Intrinsic  Options Price Term Value  (In Years)   Outstanding as of December 31, 2017 57,394 $ 4.22 5.11 $ 73  Granted — —  Exercised — —  Forfeited — —  Expired — —  Outstanding as of March 31, 2018 57,394 $ 4.22 4.86 $ 60 No stock options have been granted under the 2010 Plan since the effective date of the 2013 Plan. 2013 Plan On January 1, 2018, the annual increase in the number of shares available for issuance under the 2013 Plan was determined to be 1,203,369 shares in accordance with the automatic annual increase provisions of the 2013 Plan. As of March 31, 2018 , there were 1,728,761 shares available for future grant under the 2013 Plan. Activity related to stock options under the 2013 Plan for the three months ended March 31, 2018 , was as follows:     Weighted  Shares Weighted Average  Issuable Average Remaining Aggregate  Under Exercise Contractual Intrinsic  Options Price Term Value  (in Years)   Outstanding as of December 31, 2017 2,557,143 $ 11.45 7.41 $ 794  Granted 672,500 4.83  Exercised (1,708) 3.14  Forfeited (9,835) 8.89  Expired (21,355) 25.45  Outstanding as of March 31, 2018 3,196,745 $ 9.97 7.74 $ 470 For the three months ended March 31, 2018 , the weighted average grant date fair value of stock options granted was $3.17 . For the three months ended March 31, 2018 , the total intrinsic value of options exercised was $3 and the total received from stock option exercises was $5 . Activity related to restricted stock under the 2013 Plan for the three months ended March 31, 2018 , was as follows:     Weighted  Average Grant  Shares Date Fair Value  Unvested restricted common stock as of December 31, 2017 491,861 $ 7.59  Issued 444,500 4.83  Vested (124,142) 10.48  Forfeited (2,535) 4.77  Unvested restricted common stock as of March 31, 2018 809,684 $ 5.64 For the three months ended March 31, 2018 , the total fair value of restricted common stock vested was $ 608 . The Company did not receive cash proceeds for any of the restricted common stock issued during the three months ended March 31, 2018 . Stock-Based Compensation The Company recorded stock-based compensation expense related to stock options and restricted stock as follows:     Three Months Ended  March 31,  2018 2017  Cost of product sales and inventories $ 31 $ 40  Research and development 170 250  Selling, general and administrative 1,183 1,524  $ 1,384 $ 1,814  As of March 31, 2018 , the Company had an aggregate of $ 5,808 and $ 3,939 of unrecognized stock-based compensation expense for options outstanding and restricted stock awards, respectively, which is expected to be recognized over a weighted average period of 2.71 years and 2.22 years, respectively.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2018
Net Loss Per Share [Abstract]
Net Loss Per Share	13. Net Loss Per Share Basic and diluted net loss per share was calculated as follows:    Three Months Ended  March 31,  2018 2017  Numerator:  Net loss $ (8,548) $ (12,612)  Denominator:  Weighted average shares outstanding, basic and diluted 44,788,068 36,711,601  Net loss per share, basic and diluted $ (0.19) $ (0.34)  Stock options for the purchase of 3,254,139 and 2,653,163 shares of common stock were excluded from the computation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2018 and 2017, respectively, because those options had an anti-dilutive impact due to the net loss attributable to common stockholders incurred for the period.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Taxes [Abstract]
Income Taxes	14. Income Taxes The Company recorded no income tax expense or benefit during the three months ended March 31, 2018 and 2017, due to a full valuation allowance recognized against its deferred tax assets. The SEC issued Staff Accounting Bulletin No. 118 (“SAB 118”) on December 22, 2017. SAB 118 provides a one-year measurement period from a registrant’s reporting period that includes the Tax Cuts and Jobs Act of 2017 (“TCJA”) enactment date to allow the registrant sufficient time to obtain, prepare and analyze information to complete the accounting required under ASC 740. Although the Company made a reasonable estimate of the gross amounts of the deferred tax assets as disc ussed in the 2017 Annual Report , a final determination of the TCJA’s impact on the deferred tax assets and related valuation allowance requirements remains incomplete pending a full analysis of the provisions of the TCJA and their interpretations. The ultimate impact of the TCJA on the Company’s reported results in 2018 and beyond may differ from the estimates provided therein, possibly materially, due to, among other things, changes in interpretations and assumptions the Company has made, guidance that may be issued, and other actions the Company may take as a result of the TCJA, different from what is presently contemplated. As of March 31, 2018, the Company has not recorded incremental accounting adjustments related to the TCJA as it continues to consider interpretations of its application, however, we expect to complete the accounting by December 2018 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2018
Accumulated Other Comprehensive Loss [Abstract]
Accumulated Other Comprehensive Loss	15. Accumulated Other Comprehensive Loss The changes in accumulated other comprehensive loss, net of their related tax effects, were as follows:    Foreign Accumulated  Currency Other  Translation Comprehensive  Adjustment Loss  As of December 31, 2017 $ (7,085) $ (7,085)  Foreign currency translation adjustment 405 405  As of March 31, 2018 $ (6,680) $ (6,680) 

Legal Contingencies

Legal Contingencies	3 Months Ended
	Mar. 31, 2018
Legal Contingencies [Abstract]
Legal Contingencies	16. Legal Contingencies From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of business, including those related to patents, product liability and government investigations. Except as described below, the Company is not presently a party to any litigation which it believes to be material, and is not aware of any pending or threatened litigation against the Company which it believes could have a material effect on its financial statements. The Company accrues contingent liabilities when it is probable that a future liability has been incurred and such liability can be reasonably estimated. In February 2017, two purported class action lawsuits were filed in the United States District Court for the Southern District of New York against the Company and two of its current officers. Those cases have been consolidated into one purported class action lawsuit under the caption, In re Aratana Therapeutics, Inc. Securities Litigation, Case No. 1:17-cv-00880. The consolidated lawsuit, which was amended in August 2017, asserts claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and is premised on allegedly false and/or misleading statements, and alleged non-disclosure of material facts, regarding the Company’s business, operations, prospects and performance during the proposed class period of March 16, 2015 to March 13, 2017. The Company is vigorously defending all claims asserted, including by filing a motion to dismiss. Given the early stage of the litigation, at this time a loss is not probable or reasonably estimable. The Company currently is not a party to any threatened or pending litigation related to intellectual property. However, third parties might allege that the Company or its licensors are infringing their patent rights or that the Company is otherwise violating their intellectual property rights. Such third parties may resort to litigation against the Company or its licensors, which the Company has agreed to indemnify. With respect to some of these patents, the Company expects that it will be required to obtain licenses and could be required to pay license fees or royalties, or both. These licenses may not be available on acceptable terms, or at all. A costly license, or inability to obtain a necessary license, could have a material adverse effect on the Company’s financial condition, results of operations or cash flows.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policy)	3 Months Ended
	Mar. 31, 2018
Summary of Significant Accounting Policies [Abstract]
Business Overview	Business Overview Aratana Therapeutics, Inc., including its subsidiaries (the “Company” or “Aratana”) was incorporated on December 1, 2010 under the laws of the State of Delaware. T he Company is a pet therapeutics company focused on licensing, developing and commercializing innovative therapeutics for dogs and cats. The Company has one operating segment: pet therapeutics.
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements of the Company for the year ended December 31, 2017 and the notes thereto in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 14, 2018 (“2017 Annual Report”) . In the opinion of management, all adjustments, consisting of a normal and recurring nature, considered necessary for a fair presentation, have been included. The Company has incurred recurring losses and negative cash flows from operations and has an accumulated deficit of $235,064 as of March 31, 2018 . The Company expects to continue to generate operating losses for the foreseeable future. The Company believes that its cash, cash equivalents and short-term investments at March 31, 2018, will be sufficient to fund operations and debt obligations at least through June 30, 2019. As disclosed in Note 8 to the consolidated financial statements, the Company has a term loan and a revolving credit facility with an aggregate principal balance of $33,500 as of March 31, 2018. The loan agreement requires that the Company maintain certain minimum liquidity at all times (the greater of cash equal to fifty percent ( 50% ) of outstanding balance or remaining months’ liquidity, which is calculated on an average trailing three (3) month basis, equal to six (6) months or greater) , which as of March 31, 2018, was approximately $26,950 . If the minimum liquidity covenant is not met, the Company may be required to repay the loans prior to their scheduled maturity dates. At March 31, 2018, the Company was in compliance with all financial covenants. The Company expects an increase in its investment related to commercial activities, including procuring of inventories needed to supply the marketplace, investing to further support adoption and awareness of the Company’s marketed products and payment of milestones related to approval and commencement of commercial sales. This will impact the minimum liquidity that needs to be maintained under the loan agreement. As a result, the Company will need additional capital to fund its operations and debt obligations beyond June 30, 2019, which the Company may obtain from corporate collaborations and licensing arrangements, or other sources, such as public or private equity offerings and further debt (re)financings. The future viability of the Company beyond June 30, 2019, is dependent on its ability to raise additional capital to finance its operations, to fund on-going research and development costs, commercialization of its therapeutics and therapeutic candidates and to satisfy debt covenants. If the Company is not able to raise additional capital on terms acceptable to it, or at all, as and when needed, the Company would be forced to delay, reduce, or eliminate certain research and development programs, reduce or eliminate discretionary operating expenses or grant rights to develop and market therapeutics or therapeutic candidates that it would otherwise prefer to develop and market itself, which could otherwise adversely affect its business prospects. The Company’s failure to raise capital, as and when needed, would have a negative impact on its financial condition and its ability to pursue its business strategies as this capital is necessary for it to perform the research and development and commercial activities required to generate future revenue streams.
Consolidation	Consolidation The Company’s consolidated financial statements include its financial statements and those of its wholly-owned subsidiaries . Intercompany balances and transactions are eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from those estimates.
Revenue from Contracts with Customers	Revenue from Contracts with Customers Effective January 1, 2018, the Company adopted ASC 606 “Revenue from Contracts with Customers” (“ASC 606”) using the modified retrospective transition method. Prior to January 1, 2018, the Company recognized revenue using the guidance of ASC 605 “Revenue Recognition” (“ASC 605”). The Company recognizes revenue when its customer obtains control of the promised goods or services, in an amount that reflects the consideration which the Company expects to be entitled to in exchange for those goods or services. The Company determines revenue recognition from contracts with customers as follows: · identify the contract(s); · identify the performance obligations in the contract(s); · determine the transaction price; · allocate the transaction price to the performance obligations in the contract; and · recognize revenue wh en (or as) the Company satisfies a performance obligation. The Company’s principal revenue streams and their respective accounting treatments are discussed below and further in Note 2, “Revenue” :  (i) Product Sales, Net The Company sells its products to its customers who could either be the end users (such as veterinarians, clinics, or animal hospitals) of the product or distributors who subsequently resell the Company’s products to end users. Revenues from product sales are recognized when the customer obtains control of the Company’s product, which occurs at a point in time, upon delivery to the customer. The Company’s delivery of its products to customers constitutes a single performance obligation as there are no other promises to deliver goods or services beyond what is specified in each accepted customer order. Product sales are recorded net of applicable reserves for variable consideration, including product returns, allowances, discounts, and rebates . Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established. Components of variable consideration include product returns, allowances, discounts, and rebates. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable (generally, for credits that the Company issues for free goods provided by distributors to end customers in conjunction with promotional programs) or a current liability (generally, reserves for products that remained in the distribution channel inventories at each reporting period end that the Company expects the distributors will provide to end customers free of charge in conjunction with promotional programs). These estimates take into consideration a range of possible outcomes for the expected value (probability-weighted estimate) or relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the respective underlying contracts. The amount of variable consideration which is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Product Returns Consistent with the industry practice, the Company generally offers customers a limited right of return of damaged or expired product that has been purchased from the Company or the Company’s distributors in exchange for an unexpired product. Exchanges due to expiry are typically allowed for a period of six months after the product’s expiration date. The Company estimates the amount of its product sales that may be returned by its customers and records these estimates as a reduction of product revenues in the period the related product revenues are recognized, as well as within accrued expenses and other current liabilities, net in the consolidated balances sheets. The Company currently estimates product return liabilities using available industry data, its own sales data and data provided by the Company’s distributors such as the inventories remaining in the distribution channel. The Company has received an immaterial amount of returns to date and believes that returns of its products in future periods will be minimal. The Company does not record a return asset associated with the returned damaged or expired goods due to such asset is deemed to be fully impaired at the time of product return. Sales Discounts and Allowances The Company compensates its distributors for sales order management, data and distribution and other services through sales discounts and allowances. However, such services are not distinct from the Company’s sale of products to distributors and, therefore, these discounts and allowances are recorded as a reduction of revenue in the statements of operations, as well as a reduction to accounts receivable, net in the consolidated balance sheets.  (ii) Licensing and Collaboration Revenues Revenues derived from product out-licensing arrangements typically consist of an initial non-refundable, up-front payment at inception of the license, subsequent milestone payments contingent on the achievement of certain regulatory, development and commercial milestones, and royalties on the net sales of the Company’s products. Licenses of Intellectual Property If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the contract, the Company recognizes revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company will evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestones Revenues from achievement of milestones generally represent a form of variable consideration as the payments are likely to be contingent on the occurrence of future events. The Company estimates milestones probable to be achieved and includes in the transaction price based on either the expected value (probability-weighted estimate) or most likely amount approach. The most likely amount is used by the Company for milestone payments with a binary outcome (i.e., the Company receives all or none of the milestone payment). Milestone payments that are not within the control of the Company or the customer, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The estimated milestone-related variable consideration is only recognized as revenue when the related performance obligation is satisfied and the Company determines that it is probable that there will not be a significant reversal of cumulative revenue recognized in future periods (i.e. variable consideration constraint). At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect licensing and collaboration revenues and earnings in the period of adjustment. For milestones not able to overcome the variable consideration constraint, not considered probable or that are determined to be sales-or usage royalties, as described later, the Company recognizes revenue when the milestones are achieved. Sales-Based Royalty Revenue The Company’s sales-based royalty revenue could consist of sales-based milestones or percentage of net sales royalties. The Company recognizes sales-based royalties related to the Company’s out-licensed intellectual property when (or as) the later of the following events occurs:  · the sale occurs; or · the performance obligation to which some or all of the sales-based or usage-based royalty has been allocated has been satisfied (or partially satisfied).  Sales-based royalties revenues recorded by the Company are based on the licensee’s or sub-licensee’s sales that occurred during the relevant period. Differences between actual and estimated royalty revenues are adjusted in the period in which they become known, typically in the following quarter. If the Company is unable to reasonably estimate royalty revenue or does not have access to the information, then the Company records royalty revenue when the information needed for a reliable estimate becomes available. Royalty revenue is included in licensing and collaboration revenue in the consolidated statements of operations. The Company recognizes revenue from sales-based milestones when the milestones are achieved.
Property and Equipment, Net	Property and Equipment, Net Property and equipment is recorded at historical cost, net of accumulated depreciation and amortization of $1,310 and $1,188 , as of March 31, 2018 and December 31, 2017 , respectively.
New Accounting Standards	New Accounting Standards Revenue from Contracts with Customers In May 2014, the Financial Accounting Standards Board (“FASB”) issued guidance on recognizing revenue in contracts with customers. The guidance affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (e.g., insurance contracts or lease contracts). This guidance superseded the revenue recognition requirements in topic, Revenue Recognition , and most industry-specific guidance. The core principle of the guidance is that an entity should 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. The Company adopted this guidance on January 1, 2018. The impact of adoption is described further in Note 2 , “Revenue.” Leases In February 2016, the FASB issued guidance that requires, for operating leases, a lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted and is to be applied on a modified retrospective transition. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. The Company currently expects that its operating lease commitments will be subject to the new guidance which will result in recognition of operating lease liabilities and right-of-use assets in the consolidated balance sheets upon the adoption of the new guidance. However, the Company’s assessment of the impact of adoption is still ongoing. Compensation – Stock Compensation In May 2017, the FASB issued guidance on determining which changes to the terms or conditions of share-based payment awards require an entity to apply modification accounting. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted this guidance on January 1, 2018, and the adoption did not have a material impact on its consolidated financial statements.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue [Abstract]
Disaggregation of Revenue by Source	  Three Months Ended  March 31,  2018 2017 (1)  Revenues  Licensing and collaboration revenue  GALLIPRANT $ 1,706 $ 903  Total licensing and collaboration revenue 1,706 903  Product sales  NOCITA $ 1,547 $ 327  ENTYCE 790 —  GALLIPRANT — 2,545  Other — 20  Total product sales 2,337 2,892  Total revenues $ 4,043 $ 3,795 (1) Prior period amounts have not been adjusted under the modified retrospective method
Schedule of Change in Contract Liability Balances	  2018  As of January 1, $ 7,000  ASC 606 adoption (6,800)  Revenue recognized —  As of the end of period, $ 200 

Fair Value of Financial Asset25

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value of Financial Assets and Liabilities [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	   Fair Value Measurements as of  Carrying March 31, 2018 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,462 $ — $ 9,462 $ — $ 9,462  Short-term investments:  Short-term marketable securities - certificates of deposit 498 — 498 — 498  $ 9,960 $ — $ 9,960 $ — $ 9,960      Fair Value Measurements as of  Carrying December 31, 2017 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 8,964 $ — $ 8,964 $ — $ 8,964  Short-term investments:  Short-term marketable securities - certificates of deposit 747 — 747 — 747  $ 9,711 $ — $ 9,711 $ — $ 9,711 
Schedule of Liabilities not Measured at Fair Value on Recurring Basis	   March 31, 2018  Carrying Value Fair Value  Liabilities:  Loans payable (Level 2) $ 33,965 $ 33,807      December 31, 2017  Carrying Value Fair Value  Liabilities:  Loans payable (Level 2) $ 36,825 $ 36,973 

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Investments [Abstract]
Fair Value of Available-for-Sale Marketable Securities	   March 31, 2018  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 498 $ — $ — $ 498  Total $ 498 $ — $ — $ 498      December 31, 2017  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 747 $ — $ — $ 747  Total $ 747 $ — $ — $ 747 

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2018
Inventories [Abstract]
Components of Inventories	   March 31, 2018 December 31, 2017  Raw materials $ 627 $ 1,132  Work-in-process 11,033 12,322  Finished goods 2,292 122  $ 13,952 $ 13,576 

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
Summary of Goodwill	   Gross Impairment Net  Carrying Value Losses Carrying Value  Goodwill $ 41,683 $ — $ 41,683 
Summary of Change in the Net Book Value of Goodwill	   2018  As of January 1, $ 41,295  Effect of foreign currency exchange 388  As of the end of the period, $ 41,683 

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
Summary of Change in the Net Book Value of Other Intangible Assets	   2018  As of January 1, $ 6,616  Amortization expense (130)  As of the end of the period, $ 6,486 
Summary of Amortized Intangible Assets	   Gross Net Weighted  Carrying Accumulated Carrying Average  Value Amortization Value Useful Life  Intellectual property rights for currently marketed products $ 7,000 $ 514 $ 6,486 14.1 Years  Amortized intangible assets as of December 31, 2017, were as follows:    Gross Net Weighted  Carrying Accumulated Carrying Average  Value Amortization Value Useful Life  Intellectual property rights for currently marketed products $ 7,000 $ 384 $ 6,616 14.1 Years  Intellectual property rights for formerly marketed products 38,652 38,652 — N/A  $ 45,652 $ 39,036 $ 6,616 

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt [Abstract]
Schedule of Loan Payable Balance	  Principal amounts  Term loan, 8.41% , principal payments from February 1, 2018 through October 1, 2019 $ 28,500  Revolving credit facility, 8.41% , principal payments from November 1, 2018 through October 1, 2019 5,000  Add: accretion of final payment and termination fees 748  Less: unamortized debt issuance costs (283)  As of the end of the period $ 33,965 

Accrued Expenses and Other Cu31

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Accrued Expenses and Other Current Liabilities [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	   March 31, 2018 December 31, 2017  Payroll and related expenses $ 1,126 $ 2,314  Professional fees 206 208  Royalty expense 806 718  Interest expense 235 249  Research and development costs 57 5  Other 445 218  Total $ 2,875 $ 3,712 

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	3 Months Ended
	Mar. 31, 2018
Compensation Related Costs, Share-based Payments [Line Items]
Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Stock	   Three Months Ended  March 31,  2018 2017  Cost of product sales and inventories $ 31 $ 40  Research and development 170 250  Selling, general and administrative 1,183 1,524  $ 1,384 $ 1,814 
2010 Equity Incentive Plan [Member]
Compensation Related Costs, Share-based Payments [Line Items]
Summary of Stock Option Activity	   Weigh t ed  Shares Weighted Average  Issuable Average Remaining Aggregate  Under Exercise Contractual Intrinsic  Options Price Term Value  (In Years)   Outstanding as of December 31, 2017 57,394 $ 4.22 5.11 $ 73  Granted — —  Exercised — —  Forfeited — —  Expired — —  Outstanding as of March 31, 2018 57,394 $ 4.22 4.86 $ 60 
2013 Plan [Member]
Compensation Related Costs, Share-based Payments [Line Items]
Summary of Stock Option Activity	   Weighted  Shares Weighted Average  Issuable Average Remaining Aggregate  Under Exercise Contractual Intrinsic  Options Price Term Value  (in Years)   Outstanding as of December 31, 2017 2,557,143 $ 11.45 7.41 $ 794  Granted 672,500 4.83  Exercised (1,708) 3.14  Forfeited (9,835) 8.89  Expired (21,355) 25.45  Outstanding as of March 31, 2018 3,196,745 $ 9.97 7.74 $ 470 
Summary of Restricted Stock Activity	   Weighted  Average Grant  Shares Date Fair Value  Unvested restricted common stock as of December 31, 2017 491,861 $ 7.59  Issued 444,500 4.83  Vested (124,142) 10.48  Forfeited (2,535) 4.77  Unvested restricted common stock as of March 31, 2018 809,684 $ 5.64 

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Net Loss Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	   Three Months Ended  March 31,  2018 2017  Numerator:  Net loss $ (8,548) $ (12,612)  Denominator:  Weighted average shares outstanding, basic and diluted 44,788,068 36,711,601  Net loss per share, basic and diluted $ (0.19) $ (0.34) 

Accumulated Other Comprehensi34

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2018
Accumulated Other Comprehensive Loss [Abstract]
Summary of Changes in Accumulated Other Comprehensive Loss	   Foreign Accumulated  Currency Other  Translation Comprehensive  Adjustment Loss  As of December 31, 2017 $ (7,085) $ (7,085)  Foreign currency translation adjustment 405 405  As of March 31, 2018 $ (6,680) $ (6,680) 

Summary of Significant Accoun35

Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)
Summary Of Significant Accounting Policies [Line Items]
Date of incorporation	Dec. 1, 2010
Number of operating segments | segment	1
Accumulated deficit	$ 235,064	$ 233,316
Accumulated depreciation and amortization	1,310	$ 1,188
Payment of promissory note	3,000
Term Loan And Revolving Credit Facility [Member]
Summary Of Significant Accounting Policies [Line Items]
Principal amount of debt	33,500
Term Loan [Member]
Summary Of Significant Accounting Policies [Line Items]
Principal amount of debt	$ 28,500
Minimum liquidity requirement	50.00%
Liquidity requirement	$ 26,950

Revenue (Narrative) (Details)

Revenue (Narrative) (Details) - USD ($)	Jan. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Revenue from Contract with Customer [Line Items]
Accumulated deficit		$ (235,064,000)		$ (233,316,000)
Income tax benefit		0	$ 0
Contract liability		200,000		7,000,000
Changes to the previously estimated transaction price		0
Change in variable consideration		0
Unsatisfied performance obligations		0
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue from Contract with Customer [Line Items]
Accumulated deficit	$ 6,800,000
Income tax benefit	$ 0
NOCITA and ENTYCE [Member]
Revenue from Contract with Customer [Line Items]
Reserve for product returns and allowances		$ 145,000		$ 114,000

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenue by Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 4,043	$ 3,795
Licensing and Collaboration [Member]
Disaggregation of Revenue [Line Items]
Total revenues	1,706	903
Product Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues	2,337	2,892
Product Sales [Member] | NOCITA [Member]
Disaggregation of Revenue [Line Items]
Total revenues	1,547	327
Product Sales [Member] | ENTYCE [Member]
Disaggregation of Revenue [Line Items]
Total revenues	$ 790
Product Sales [Member] | GALLIPRANT [Member]
Disaggregation of Revenue [Line Items]
Total revenues		2,545
Product Sales [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues		$ 20

Reveneue (Schedule of Change in

Reveneue (Schedule of Change in Contract Liability Balances) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue [Abstract]
As of January 1,	$ 7,000
ASC 606 adoption	(6,800)
Revenue recognized
As of the end of period,	$ 200

Fair Value of Financial Asset39

Fair Value of Financial Assets and Liabilities (Narrative) (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value	$ 9,960,000	$ 9,711,000
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value	0	0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value	$ 0	$ 0

Fair Value of Financial Asset40

Fair Value of Financial Assets and Liabilities (Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Assets, fair value	$ 9,960	$ 9,711
Carrying Value [Member]
Assets:
Assets, fair value	9,960	9,711
Certificates of Deposit [Member]
Assets:
Cash equivalents	9,462	8,964
Certificates of Deposit [Member] | Carrying Value [Member]
Assets:
Cash equivalents	9,462	8,964
Short-Term Marketable Securities - Certificates Of Deposit [Member]
Assets:
Short-term marketable securities - certificates of deposit	498	747
Short-Term Marketable Securities - Certificates Of Deposit [Member] | Carrying Value [Member]
Assets:
Short-term marketable securities - certificates of deposit	498	747
Level 2 [Member]
Assets:
Assets, fair value	9,960	9,711
Level 2 [Member] | Certificates of Deposit [Member]
Assets:
Cash equivalents	9,462	8,964
Level 2 [Member] | Short-Term Marketable Securities - Certificates Of Deposit [Member]
Assets:
Short-term marketable securities - certificates of deposit	$ 498	$ 747

Fair Value of Financial Asset41

Fair Value of Financial Assets and Liabilities (Schedule of Liabilities not Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan payable, Carrying Value	$ 33,965
Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan payable, Carrying Value	33,965	$ 36,825
Loan payable, Fair Value	$ 33,807	$ 36,973

Investments (Fair Value of Avai

Investments (Fair Value of Available-for-Sale Marketable Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 498	$ 747
Fair Value	498	747
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	498	747
Fair Value	$ 498	$ 747

Inventories (Narrative) (Detail

Inventories (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventory [Line Items]
Non-cancellable open orders	$ 2,687	$ 7,132
Raw materials	$ 627	1,132
GALLIPRANT [Member]
Inventory [Line Items]
Raw materials		$ 777

Inventories (Components of Inve

Inventories (Components of Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Inventories [Abstract]
Raw materials	$ 627	$ 1,132
Work-in-process	11,033	12,322
Finished goods	2,292	122
Total	$ 13,952	$ 13,576

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)
Goodwill and Intangible Assets [Abstract]
Goodwill impairment loss	$ 0

Goodwill (Summary of Goodwill)

Goodwill (Summary of Goodwill) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets [Abstract]
Gross Carrying Value	$ 41,683
Impairment Losses
Net Carrying Value	$ 41,683	$ 41,295

Goodwill (Summary of Change in

Goodwill (Summary of Change in the Net Book Value of Goodwill) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Goodwill and Intangible Assets [Abstract]
As of January 1,	$ 41,295
Effect of foreign currency exchange	388
As of the end of the period,	$ 41,683

Intangible Assets, Net (Narrati

Intangible Assets, Net (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Goodwill and Intangible Assets [Abstract]
Amortization of intangible assets	$ 130	$ 64
Intangible assets, net	$ 6,486		$ 6,616

Intangible Assets, Net (Summary

Intangible Assets, Net (Summary of Change in the Net Book Value of Other Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets [Abstract]
As of January 1,	$ 6,616
Amortization expense	(130)	$ (64)
As of the end of the period,	$ 6,486

Intangible Assets, Net (Summa50

Intangible Assets, Net (Summary of Amortized Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying value		$ 45,652
Accumulated amortization		39,036
Net carrying value		6,616
Intellectual Property Rights For Currently Marketed Products [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 7,000	7,000
Accumulated amortization	514	384
Net carrying value	$ 6,486	$ 6,616
Weighted average useful life	14 years 1 month 6 days	14 years 1 month 6 days
Intellectual Property Rights For Formerly Marketed Products [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying value		$ 38,652
Accumulated amortization		38,652
Net carrying value

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	Oct. 17, 2017	Jul. 31, 2017	Oct. 16, 2015	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Interest expense				$ 853,000	$ 860,000
Amortization of debt issuance costs				140,000	119,000
Interest expense				853,000	$ 860,000
Current portion – loans payable				20,083,000		$ 17,333,000
Term Loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 35,000,000
Aggregate principal amount borrowed				28,500,000
Principal amount of debt				$ 28,500,000
Interest rate				8.41%
Minimum liquidity requirement				50.00%
Liquidity requirement				$ 26,950,000
Current portion – loans payable				18,000,000
Revolving Line due 2017 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 5,000,000
Amount outstanding				$ 5,000,000
Termination commitment fee percentage				3.30%
Unused capacity commitment fee percentage				0.25%
Date of maturity				Oct. 16, 2017
Termination fee				$ 165,000
Termination fee paid	$ 165,000
Current portion – loans payable				2,083,000
Revolving Line due 2019 [Member]
Debt Instrument [Line Items]
Principal amount of debt				$ 5,000,000
Interest rate				8.41%
Term Loan And Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal amount of debt				$ 33,500,000
Interest rate			6.91%	8.41%
Excess interest rate over prime rate			3.66%
Loan Agreement, Second Amendment [Member]
Debt Instrument [Line Items]
Facility fee		$ 60,000
Interest only payment term		6 months
Date of maturity				Oct. 16, 2019
Amendment fee		$ 150,000
Termination fee		$ 165,000
Additional default interest rate				4.00%
Minimum liquidity requirement				50.00%
Liquidity requirement				$ 26,950,000

Debt (Schedule of Loan Payable

Debt (Schedule of Loan Payable Balance) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Debt Instrument [Line Items]
Add: accretion of final payment and termination fees	$ 748
Less: unamortized debt issuance costs	(283)
Total	33,965
Term Loan [Member]
Debt Instrument [Line Items]
Principal amounts	$ 28,500
Interest rate	8.41%
Date of first principal payment	Feb. 1, 2018
Date of final principal payment	Oct. 1, 2019
Revolving Line due 2019 [Member]
Debt Instrument [Line Items]
Principal amounts	$ 5,000
Interest rate	8.41%
Date of first principal payment	Nov. 1, 2018
Date of final principal payment	Oct. 1, 2019

Accrued Expenses and Other Cu53

Accrued Expenses and Other Current Liabilities (Summary of Accrued Expenses and Other Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accrued expenses:
Payroll and related expenses	$ 1,126	$ 2,314
Professional fees	206	208
Royalty expense	806	718
Interest expense	235	249
Research and development costs	57	5
Other	445	218
Total	$ 2,875	$ 3,712

Agreements (RaQualia Pharma Inc

Agreements (RaQualia Pharma Inc Narrative) (Details) - RaQualia Agreements [Member] $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2019USD ($)	Dec. 27, 2010USD ($)agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of license agreements | agreement			2
Milestones paid	$ 11,500
Scenario, Forecast [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones achieved		$ 2,000
GALLIPRANT [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable			$ 4,000
ENTYCE [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable			$ 3,000

Agreements (Elanco GALLIPRANT N

Agreements (Elanco GALLIPRANT Narrative) (Details) - USD ($)	Apr. 28, 2017	Sep. 30, 2017	Mar. 31, 2018	Dec. 31, 2017
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Licensing and collaboration commitment			$ 200,000	$ 7,000,000
ASC 606 adoption			6,800,000
Contract liability			200,000	7,000,000
Elanco Collaboration Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non-refundable, non-creditable up-front payment receivable			45,000,000
Milestone receivable			0
Licensing and collaboration commitment			200,000	7,000,000
ASC 606 adoption			6,800,000
Contract liability			$ 200,000	$ 7,000,000
Elanco Collaboration Agreement [Member] | Grapiprant Products [Member] | Aratana [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percentage of third-party development fees and expenses to be paid			25.00%
Elanco Collaboration Agreement [Member] | Elanco Animal Health, Inc. [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Percentage of third-party development fees and expenses to be paid			75.00%
Elanco Collaboration Agreement Amendment [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Binding purchase order, submission period	15 days
Agreement to pay after proof of payment to manufacturer, period	30 days
Cash paid for contingent consideration		$ 10,832,000
Elanco Co-Promotion Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fee for services performed and expenses incurred as a percent of gross margin to net sales			25.00%
European Approval Milestone [Member] | Elanco Collaboration Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone receivable			$ 4,000,000
Manufacturing Milestone [Member] | Elanco Collaboration Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone receivable			4,000,000
Sales Milestone [Member] | Elanco Collaboration Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone receivable			$ 75,000,000
Reduction for each annual occurrence milestone is not achieved			33.33%

Agreements (Vet-Stem, Inc. Narr

Agreements (Vet-Stem, Inc. Narrative) (Details)	3 Months Ended
	Mar. 31, 2018USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
In-process research and development	$ 500,000
AT-016 [Member] | Vet-Stem Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
In-process research and development	0
Milestones payable	$ 0

Agreements (AskAt Inc. Narrativ

Agreements (AskAt Inc. Narrative) (Details) - USD ($) $ in Thousands	Feb. 28, 2018	Mar. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
In-process research and development		$ 500
AskAt Collaboration And Option Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront option fee		500
AT-019 [Member] | AskAt Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License fee	$ 500
In-process research and development		$ 500
Milestones payable	15,500
Net sales that must be met for milestone payable	$ 100,000
Percentage of milestone payable that can be paid out in cash	50.00%
Percentage of milestone payable that can be paid out in shares	50.00%
AT-019 [Member] | AskAt Agreement [Member] | Maximum [Member] | Clinical Development And Regulatory Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	$ 3,000
AT-019 [Member] | AskAt Agreement [Member] | Maximum [Member] | Commercial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	$ 12,500

Common Stock (Narrative) (Detai

Common Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 18, 2017	Mar. 31, 2018	Mar. 31, 2017	May 04, 2018	Dec. 31, 2017	Aug. 04, 2017
Class of Stock [Line Items]
Common stock, authorized		100,000,000			100,000,000
Common stock, par value		$ 0.001			$ 0.001
Common stock, shares outstanding		46,033,850			42,532,725
Treasury stock, shares		89,604			80,916
Treasury stock, value		$ 1,149			$ 1,107
Restricted stock withheld to satisfy employee tax withholding, shares		8,688	1,342
Restricted stock withheld to satisfy employee tax withholding, per share		$ 4.90	$ 7.88
Proceeds from offering		$ 15,614	$ 1,223
At-the-Market Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Placement agent fee		483
Offering expense		$ 117
Aggregate stock available to sell	$ 50,000
Percentage of commission on gross proceeds from sale of shares	3.00%
Shares issued		3,383,963
Proceeds from offering		$ 15,498
Shelf Registration Statement [Member]
Class of Stock [Line Items]
Aggregate stock available to sell						$ 100,000
Subsequent Event [Member] | At-the-Market Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Remaining stock available to sell				$ 33,900
2013 Plan [Member]
Class of Stock [Line Items]
Unvested restricted common stock outstanding		809,684			491,861

Stock-Based Awards (Narrative)

Stock-Based Awards (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2018	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from stock option exercises		$ 5	$ 6
Accumulated deficit		$ 235,064		$ 235,064	$ 233,316
2010 Equity Incentive Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted				0
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant		1,728,761		1,728,761
Stock options granted		672,500
Annual increase in shares	1,203,369
Weighted average grant date fair value, grants		$ 4.83
Unrecognized stock-based compensation expense for options outstanding		$ 5,808		$ 5,808
Unrecognized stock-based compensation expense, other than options		3,939		$ 3,939
2013 Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised		3
Proceeds from stock option exercises		$ 5
Weighted average grant date fair value of options granted		$ 3.17
Unrecognized stock-based compensation expense, recognition period		2 years 8 months 16 days
2013 Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value stock awards, vested, other than options		$ 608
Proceeds from the issuance of restricted stock		$ 0
Unrecognized stock-based compensation expense, recognition period		2 years 2 months 19 days

Stock-Based Awards (Summary of

Stock-Based Awards (Summary of Stock Option Activity) (Details) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares
2010 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issuable Under Options, Outstanding as of December 31, 2017 | shares	57,394
Shares Issuable Under Options, Outstanding as of March 31, 2018 | shares	57,394	57,394
Weighted Average Exercise Price, Outstanding as of December 31, 2017 | $ / shares	$ 4.22
Weighted Average Exercise Price, Outstanding as of March 31, 2018 | $ / shares	$ 4.22	$ 4.22
Weighted Average Remaining Contractual Term, Outstanding	4 years 10 months 10 days	5 years 1 month 10 days
Aggregate Intrinsic Value, Outstanding | $	$ 60	$ 73
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issuable Under Options, Outstanding as of December 31, 2017 | shares	2,557,143
Shares Issuable Under Options, Granted | shares	672,500
Shares Issuable Under Options, Exercised | shares	(1,708)
Shares Issuable Under Options, Forfeited | shares	(9,835)
Shares Issuable Under Options, Expired | shares	(21,355)
Shares Issuable Under Options, Outstanding as of March 31, 2018 | shares	3,196,745	2,557,143
Weighted Average Exercise Price, Outstanding as of December 31, 2017 | $ / shares	$ 11.45
Weighted Average Exercise Price, Granted | $ / shares	4.83
Weighted Average Exercise Price, Exercised | $ / shares	3.14
Weighted Average Exercise Price, Forfeited | $ / shares	8.89
Weighted Average Exercise Price, Expired | $ / shares	25.45
Weighted Average Exercise Price, Outstanding as of March 31, 2018 | $ / shares	$ 9.97	$ 11.45
Weighted Average Remaining Contractual Term, Outstanding	7 years 8 months 27 days	7 years 4 months 28 days
Aggregate Intrinsic Value, Outstanding | $	$ 470	$ 794

Stock-Based Awards (Summary o61

Stock-Based Awards (Summary of Restricted Stock Activity) (Details) - 2013 Plan [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted common stock as of December 31, 2017, Shares | shares	491,861
Issued, Shares | shares	444,500
Vested, Shares | shares	(124,142)
Forfeited, Shares | shares	(2,535)
Unvested restricted common stock as of March 31, 2018, Shares | shares	809,684
Unvested restricted common stock as of December 31, 2017, Weighted Average Grant Date Fair Value | $ / shares	$ 7.59
Issued, Weighted Average Grant Date Fair Value | $ / shares	4.83
Vested, Weighted Average Grant Date Fair Value | $ / shares	10.48
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	4.77
Unvested restricted common stock as of March 31, 2018, Weighted Average Grant Date Fair Value | $ / shares	$ 5.64

Stock-Based Awards (Summary o62

Stock-Based Awards (Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Stock) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,384	$ 1,814
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	170	250
Cost of Product Sales and Inventories [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	31	40
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,183	$ 1,524

Net Loss Per Share (Narrative)

Net Loss Per Share (Narrative) (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stock Options [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock excluded from diluted net loss per share	3,254,139	2,653,163

Net Loss Per Share (Schedule of

Net Loss Per Share (Schedule of Basic and Diluted Net Loss per Share Attributable to Common Stockholders) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net loss	$ (8,548)	$ (12,612)
Denominator:
Weighted average shares outstanding, basic and diluted	44,788,068	36,711,601
Net loss per share, basic and diluted	$ (0.19)	$ (0.34)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Taxes [Abstract]
Income tax benefit recognized	$ 0	$ 0

Accumulated Other Comprehensi66

Accumulated Other Comprehensive Loss (Summary of Changes in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2017	$ (7,085)
Foreign currency translation adjustment	405	$ 299
As of March 31, 2018	(6,680)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
As of December 31, 2017	(7,085)
Foreign currency translation adjustment	405
As of March 31, 2018	$ (6,680)

Legal Contingencies (Narrative)

Legal Contingencies (Narrative) (Details) - Purported Class Action Lawsuit [Member]	1 Months Ended
	Feb. 28, 2017lawsuititem
Commitments And Contingencies [Line Items]
Number of lawsuits	2
Number of lawsuits after consolidation	1
Officers [Member]
Commitments And Contingencies [Line Items]
Number of individuals named | item	2