Aratana Therapeutics (PETX) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 03, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	ARATANA THERAPEUTICS, INC.
Entity Central Index Key	0001509190
Current Fiscal Year End Date	--12-31
Trading Symbol	PETX
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		48,969,374

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 36,561	$ 41,431
Short-term investments	496	1,240
Accounts receivable, net	4,859	2,204
Inventories	10,828	11,425
Prepaid expenses and other current assets	1,178	1,827
Total current assets	53,922	58,127
Property and equipment, net	575	693
Operating lease right-of-use asset	744
Goodwill	40,846	40,846
Intangible assets, net	7,956	6,099
Restricted cash	351	351
Other long-term assets	318	320
Total assets	104,712	106,436
Current liabilities:
Accounts payable	2,969	911
Accrued expenses and other current liabilities	4,729	4,646
Current portion – operating lease liability	398
Total current liabilities	8,096	5,557
Operating lease liability	398
Other long-term liabilities		57
Total liabilities	8,494	5,614
Commitments and contingencies (Notes 5, 15 and 16)
Stockholders' equity:
Common stock, $0.001 par value; 100,000,000 shares authorized at March 31, 2019 and December 31, 2018 and 48,347,297 and 48,048,914 issued and outstanding at March 31, 2019 and December 31, 2018, respectively	48	48
Treasury stock, at cost; 129,603 and 94,107 shares at March 31, 2019 and December 31, 2018, respectively	(1,325)	(1,175)
Additional paid-in capital	353,078	350,745
Accumulated deficit	(248,025)	(241,238)
Accumulated other comprehensive loss	(7,558)	(7,558)
Total stockholders' equity	96,218	100,822
Total liabilities and stockholders' equity	$ 104,712	$ 106,436

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
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	48,347,297	48,048,914
Common stock, shares outstanding	48,347,297	48,048,914
Treasury stock, shares	129,603	94,107

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues
Total revenues	$ 7,360	$ 4,043
Costs and expenses
Cost of product sales	1,519	536
Royalty expense	1,692	806
Research and development	1,775	2,205
Selling, general and administrative	9,193	7,699
Amortization of intangible assets	143	130
In-process research and development		500
Total costs and expenses	14,322	11,876
Loss from operations	(6,962)	(7,833)
Other income (expense)
Interest income	174	141
Interest expense		(853)
Other income (expense), net	1	(3)
Total other income (expense)	175	(715)
Net loss	$ (6,787)	$ (8,548)
Net loss per share, basic and diluted	$ (0.14)	$ (0.19)
Weighted average shares outstanding, basic and diluted	48,277,129	44,788,068
Licensing and Collaboration [Member]
Revenues
Total revenues	$ 3,387	$ 1,706
Product Sales [Member]
Revenues
Total revenues	$ 3,973	$ 2,337

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Consolidated Statements of Comprehensive Loss [Abstract]
Net loss	$ (6,787)	$ (8,548)
Other comprehensive income:
Foreign currency translation adjustment		405
Other comprehensive income		405
Comprehensive loss	$ (6,787)	$ (8,143)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock Outstanding [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock At Cost [Member]	Total
Balance at Dec. 31, 2017	$ 43	$ 321,599	$ (233,316)	$ (7,085)	$ (1,107)	$ 80,134
Balance, shares at Dec. 31, 2017	42,532,725
At-the-Market issuance of common stock, net of issuance costs	$ 3	15,495				15,498
At-the-Market issuance of common stock, net of issuance costs, shares	3,383,963
Compensation expense related to stock options and restricted awards		1,384				1,384
Vesting of restricted stock awards, shares	124,142
Repurchase of common stock					(42)	(42)
Repurchase of common stock, shares	(8,688)
Issuance of common stock related to option exercises		5				5
Issuance of common stock related to option exercises, shares	1,708
ASC 606 adoption adjustment			6,800			6,800
Other comprehensive income				405		405
Net loss			(8,548)			(8,548)
Balance at Mar. 31, 2018	$ 46	338,483	(235,064)	(6,680)	(1,149)	95,636
Balance, shares at Mar. 31, 2018	46,033,850
Balance at Dec. 31, 2018	$ 48	350,745	(241,238)	(7,558)	(1,175)	100,822
Balance, shares at Dec. 31, 2018	48,048,914
Compensation expense related to stock options and restricted awards		2,306				2,306
Vesting of restricted stock awards, shares	325,057
Repurchase of common stock					(150)	(150)
Repurchase of common stock, shares	(35,496)
Issuance of common stock related to option exercises		27				27
Issuance of common stock related to option exercises, shares	8,822
Net loss			(6,787)			(6,787)
Balance at Mar. 31, 2019	$ 48	$ 353,078	$ (248,025)	$ (7,558)	$ (1,325)	$ 96,218
Balance, shares at Mar. 31, 2019	48,347,297

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Consolidated Statements of Changes in Stockholders' Equity [Abstract]
At-the-Market issuance of common stock, issuance cost	$ 117

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net loss	$ (6,787)	$ (8,548)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,306	1,384
Depreciation and amortization expense	261	249
Non-cash interest expense		140
Changes in operating assets and liabilities:
Accounts receivable, net	(2,655)	(32)
Inventories	597	(376)
Prepaid expenses and other current assets	649	360
Other assets	91	10
Accounts payable	58	(5,561)
Accrued expenses and other liabilities	(11)	(840)
Net cash used in operating activities	(5,491)	(13,214)
Cash flows from investing activities
Purchase of investments	(496)	(498)
Proceeds from maturities of investments	1,240	747
Net cash provided by investing activities	744	249
Cash flows from financing activities
Taxes paid for awards vested under equity incentive plans	(150)	(42)
Proceeds from stock option exercises	27	5
Proceeds from issuance of common stock, net of commissions and underwriter fees		15,614
Payments for common stock issuance costs		(57)
Payments on loans payable		(3,000)
Net cash provided by (used in) financing activities	(123)	12,520
Effect of exchange rate on cash		4
Net decrease in cash, cash equivalents and restricted cash	(4,870)	(441)
Cash, cash equivalents and restricted cash, beginning of period	41,782	67,218
Cash, cash equivalents and restricted cash, end of period	36,912	66,777
Supplemental disclosure of cash flow information
Cash paid for interest		728
Supplemental disclosure of noncash investing and financing activities:
Unpaid common stock issuance costs included in accounts payable		$ 38
Milestone capitalized as an intangible asset included in accounts payable	$ 2,000

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
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 the development and commercialization of 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, 2018 and the notes thereto in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission ( the “SEC”) on March 1 3 , 201 9 . 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 $248,025 as of March 31, 2019 . 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, 2019 , will be sufficient to fund operations for at least one year from the issuance of these consolidated financial statements. The Company expects continued 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. As a result, if the Company cannot generate sufficient cash flow from operations in the future, the Company will seek to fund its operations through corporate collaborations and licensing arrangements, or other sources, such as public or private equity and further debt financings. 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 US subsidiary and a foreign subsidiary through its dissolution date in December 2018. 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. Property and Equipment, Net Property and equipment is recorded at historical cost, net of accumulated depreciation and amortization of $1,781 and $1,661 , as of March 31, 2019 and December 31, 2018, respectively. Leases Effective January 1, 2019, the Company adopted ASC Topic 842 “Leases” ( the “ASC 842”) using the modified retrospective transition approach. Prior to January 1, 2019, the Company recorded leases under ASC Topic 840 “Leases” (the “ASC 840”) . The Company determines if an arrangement is a lease at contract inception. Operating leases are included in operating lease right-of-use (“ROU”) assets, lease liabilities – current portion (included in current liabilities) and lease liabilities (included in long-term liabilities) in the consolidated balance sheet as of March 31, 2019 . Operating lease ROU assets represent the right to use an underlying asset for the lease term and operating lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. The lease term includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit rate when it is readily determinable. If leases do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The Company gives consideration to its prior debt issuances as well as publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates. The lease payments used to determine the operating lease ROU assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized in the operating lease assets in the consolidated balance sheets. In addition, lease contracts may contain lease and nonlease components. The Company does not separate nonlease components from their related lease components. The Company excludes short-term leases (term of twelve months or less) from the balance sheet presentation. Lease expense is recognized on a straight-line basis over the lease term. New Accounting Standards Intangibles – Goodwill and Other – Internal-Use Software In August 2018, the FASB issued guidance that largely aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The guidance provides criteria for determining which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The capitalized implementation costs are required to be expensed over the term of the hosting arrangement. The guidance also clarifies the presentation requirements for reporting such costs in the entity’s financial statements. The guidance is effective for financial statements issued for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. Fair Value Measurements In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance eliminates, modifies and adds disclosure requirements for fair value measurements. The guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. Compensation – Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued guidance that largely aligns the accounting for share-based payment awards issued to employees and nonemployees. Under the new guidance, the existing employee guidance generally will apply to nonemployee share-based transactions, with the exception of specific guidance related to inputs to an option pricing model and the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. In addition, the contractual term will be able to be used in lieu of an expected term in the option-pricing model for nonemployee awards. 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, including in interim periods, but no earlier than an entity’s adoption of ASC 606 . The Company adopted this guidance on January 1, 2019, and the adoption did not have a material impact on its consolidated financial statements. 

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenue [Abstract]
Revenue	2. Revenue Disaggregated Revenues The following table presents the Company’s revenues disaggregated by revenue source. All product sales are derived from United States sources and sales taxes are excluded from revenues.     Three Months Ended  March 31,  2019 2018  Revenues  Licensing and collaboration revenue  GALLIPRANT $ 3,387 $ 1,706  Total licensing and collaboration revenue 3,387 1,706  Product sales  NOCITA $ 2,499 $ 1,547  ENTYCE 1,474 790  Total product sales 3,973 2,337  Total revenues $ 7,360 $ 4,043 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 sales, and distributor product sales revenues consist primarily of ENTYCE sales. As of March 31, 2019 and December 31, 2018, reserves for NOCITA and ENTYCE product returns were $237 and $222 , respectively. Licensing and Collaboration Revenue The Company generates licensing and collaboration revenue solely from the Collaboration, License, Development and Commercialization Agreement (as amended, the “Collaboration Agreement”) and Co-Promotion Agreement (collectively, “the Elanco Agreements”) with Elanco Animal Health, Inc. (“Elanco”) 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; and · regulatory milestones from the Collaboration Agreement that are recognized as revenue if and when achieved. Unsatisfied Performance Obligations As of March 31, 2019, the Company had no unsatisfied performance obligations.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
	Mar. 31, 2019
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, 2019 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,672 $ — $ 9,672 $ — $ 9,672  Short-term investments:  Short-term marketable securities - certificates of deposit 496 — 496 — 496  $ 10,168 $ — $ 10,168 $ — $ 10,168      Fair Value Measurements as of  Carrying December 31, 2018 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,424 $ — $ 9,424 $ — $ 9,424  Short-term investments:  Short-term marketable securities - certificates of deposit 1,240 — 1,240 — 1,240  $ 10,664 $ — $ 10,664 $ — $ 10,664 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, 2019 and December 31, 2018 .

Investments

Investments	3 Months Ended
	Mar. 31, 2019
Investments [Abstract]
Investments	4. Investments Marketable Securities Marketable securities consisted of the following:     March 31, 2019  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 496 $ — $ — $ 496  Total $ 496 $ — $ — $ 496      December 31, 2018  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 1,240 $ — $ — $ 1,240  Total $ 1,240 $ — $ — $ 1,240 At March 31, 2019 and December 31, 2018 , 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, 2019
Inventories [Abstract]
Inventories	5. Inventories Inventories are stated at the lower of cost and net realizable value and consisted of the following:      March 31, 2019 December 31, 2018  Raw materials $ 121 $ 242  Work-in-process 7,607 8,999  Finished goods 3,100 2,184  $ 10,828 $ 11,425 As of March 31, 2019 , the Company had non-cancellable open orders for the purchase of inventories of $ 2,094 , w hich is expected to be paid in the next twelve months.

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2019
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, 2019 , was as follows:      Gross Impairment Net  Carrying Value Losses Carrying Value  Goodwill $ 40,846 $ — $ 40,846  

Intangible Assets, Net

Intangible Assets, Net	3 Months Ended
	Mar. 31, 2019
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, 2019 , was as follows:     2019  As of January 1, $ 6,099  Additions 2,000  Amortization expense (143)  Impairment —  As of the end of the period, $ 7,956 The Company recognized amortization expense of $143 and $130 for the three months ended March 31, 2019 and 2018, respectively. Amortized Intangible Assets Amortized intangible assets as of March 31, 2019 , 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 $ 9,000 $ 1,044 $ 7,956 13.6 Years Amortized intangible assets as of December 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 $ 901 $ 6,099 14.1 Years Unfavorable estimates of the Company’s therapeutics’ market opportunities or unfavorable outcomes of the Company’s development activities, expected future cash flows and estimated useful lives could result in impairment charges in future periods. As of March 31, 2019 and December 31, 2018 , 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, 2019
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 the Pacific Western Bank, as a collateral 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 (the “Term Loan”) and a revolving credit facility in an aggregate principal amount up to $5,000 (the “Revolving Line”), subject to certain conditions to funding. The Term Loan and the Revolving Line bore interest per annum at the greater of (i) 6.91% or (ii) 3.66% plus the prime rate. On December 21, 2018, the Company repaid in full all outstanding indebtedness and terminated all commitments and obligations under its Loan Agreement between the Borrowers and the Lenders. D uring the three months ended March 31, 2018, the Company recognized interest expense of $853 and a mortization of debt issuance costs and accretion of final payment and termination fees of $140 , recognized as interest expense .

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2019
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, 2019 December 31, 2018  Payroll and related expenses $ 1,514 $ 2,587  Professional fees 505 353  Royalty expense 1,712 812  Research and development costs 326 73  Accrued loss on a firm purchase commitment — 72  Other 672 749  Total $ 4,729 $ 4,646 

Agreements

Agreements	3 Months Ended
	Mar. 31, 2019
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 $2,000 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, 2019, the Company had paid $11,500 in milestone payments since the execution of the RaQualia Agreements . The Company achieved a $2,000 milestone during the three months ended March 31, 2019, which was capitalized as an intangible asset. This milestone was included in the accounts payable as of March 31, 2019, and is expected to be paid in the second quarter of 2019 . The Company does not expect to achieve any milestones related to the RaQualia A greements in the next the twelve months. Pacira Pharmaceuticals, Inc. (“Pacira”) On December 5, 2012, the Company entered into an Exclusive License, Development, and Commercialization Agreement with Pacira (the “Pacira License Agreement”) that granted the Company global rights for development and commercialization of licensed animal health products for NOCITA (also known as AT-003). On the same date, the Company also entered into a supply agreement with Pacira (the “Pacira Supply Agreement”, and together with the Pacira License Agreement, the “Pacira Agreements”). On July 5, 2018 (the “Effective Date”), the Company and Pacira entered into an amendment and restatement of the Pacira License Agreement (“A&R License Agreement”) and an amendment and restatement of the Pacira Supply Agreement (the “A&R Supply Agreement”). Under the A&R Supply Agreement, Pacira has agreed to manufacture and supply the licensed product in a 10 mL vial size in addition to the 20 mL vial size that is currently supplied to the Company. The supply price for the 10 mL vial size will remain fixed until December 31, 2021. Prior to December 31, 2021, the Company and Pacira have agreed to negotiate in good faith the applicable terms related to the 10 mL vial, including the price, for after December 31, 2021. If the Company and Pacira are unable to reach agreement, then as of January 1, 2022, and on each anniversary thereafter during the term of the A&R Supply Agreement, the price for the 10 mL vial will be automatically increased by a low single-digit percentage. The A&R License Agreement amended various sections of the Pacira License Agreement, including milestone payments and royalties, to incorporate the introduction of the 10 mL vial size. Prior to December 31, 2021, the Company will not be obligated to pay any royalty payments to Pacira on the sales of the 10 mL vial and thereafter, the Company and Pacira have agreed to negotiate in good faith the applicable terms relating to the 10 mL vial in accordance with the A&R Supply Agreement. The tiered royalties on the Company’s product sales of 20 mL vials remain unchanged. In addition, the A&R License Agreement reduces the annual net sales thresholds for achieving each of the potential commercial milestone payments owed to Pacira. The remaining $40,000 of commercial milestones per the A&R License Agreement begin to be triggered once NOCITA annual net sales reach $50,000 with the final tier being owed to Pacira once NOCITA annual net sales reach $250,000 . Further, the A&R License Agreement lowered the minimum annual revenue payment to be provided to Pacira by the Company and delayed by one year the first period in which this minimum annual revenue payment requirement would be triggered such that the period is now expected to commence on January 1, 2023. The definition of a competing product was specified and narrowed to those injectable analgesic products preventing pain for at least forty-eight to seventy-two hours post-surgery as an active pharmaceutical ingredient (“API”) labeled for the control of post-operative pain for surgical veterinary use. The term of the A&R License Agreement was extended with the initial term commencing as of the new Effective Date. As of March 31, 2019, the Company had paid $2,500 in milestone payments since execution of the Pacira Agreements , and no milestone payments were accrued . No milestones were achieved during the three months ended March 31, 2019. The Company does not expect to achieve any milestones related to the A&R Agreement in the next twelve months . On April 26, 2019, the Company and Pacira entered into an amendment to the A&R License Agreement . Th is a mendment revise d certain terms related to the restrictions on competition set forth in the A&R License Agreement . Elanco GALLIPRANT On April 22, 2016, the Company entered into a 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, of which $15,000 was achieved in 2018. 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. On April 22, 2016, in connection with the Collaboration Agreement, the Company entered into a Co-Promotion Agreement (the “Co-Promotion Agreement”) with Elanco 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, and (ii) a mid-single digit percentage of net sales of Grapiprant Product in the United States after December 31, 2018 through 2028 (unless extended by mutual agreement). As of March 31, 2019, the Company had earned, and had been paid by Elanco, sales milestones totaling $15,000 , and no milestone payments were accrued. The Company will recognize revenue from any additional milestones if and when they are achieved by Elanco. 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 and paid in the second quarter of 2018. The Company will be required to pay remaining milestone payments of up to $15,500 upon the Company’s achievement of milestones, including $3,000 of development/regulatory milestones and $12,500 of commercial milestones as the 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, 2019, the Company had no t 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 an option agreement for multiple therapeutic candidates with potential in pain, allergy and cancer. D uring the first quarter of 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. In December 2018, the Company exercised its right to terminate the COA, and on February 18, 2019, the termination became effective. As a result of the termination of the COA, the Company does not anticipate mak ing any further COA-related payments to AskAt.

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2019
Common Stock [Abstract]
Common Stock	11. Common Stock Authorized Common Stock As of March 31, 2019 and December 31, 2018 , 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, 2019 and December 31, 2018 , there were 48,347,297 and 48,048,914 shares of the Company’s common stock outstanding, net of 622,431 and 535,599 shares of unvested restricted common stock, respectively. Treasury Stock As of March 31, 2019 and December 31, 2018 , there were 129,603 and 94,107 shares of the Company’s common stock held as treasury stock at a cost of $1,325 and $1,175 , respectively. During the three months ended March 31, 2019 and 201 8 , 35,496 and 8,688 shares of restricted stock at a cost of $4.22 and $4.90 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 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 $24,852 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, 2019
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, 2019 , 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, 2018 53,383 $ 4.12 4.10 $ 107  Granted — —  Exercised — —  Forfeited — —  Expired — —  Outstanding as of March 31, 2019 53,383 $ 4.12 3.85 $ 48 No stock options have been granted under the 2010 Plan since the effective date of the 2013 Plan. 2013 Plan On January 1, 201 9 , 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, 2019 , there were 2,173,138 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, 2019 , 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, 2018 3,114,401 $ 9.86 6.85 $ 2,047  Granted 740,146 4.26  Exercised (8,822) 3.14  Forfeited (226,835) 5.73  Expired (65,054) 7.39  Outstanding as of March 31, 2019 3,553,836 $ 9.02 5.93 $ 160 For the three months ended March 31, 2019 , the weighted average grant date fair value of stock options granted was $2.68 . For the three months ended March 31, 2019 , the total intrinsic value of options exercised was $9 and the total received from stock option exercises was $27 . Activity related to restricted stock under the 2013 Plan for the three months ended March 31, 2019 , was as follows:     Weighted  Average Grant  Shares Date Fair Value  Unvested restricted common stock as of December 31, 2018 535,599 $ 5.50  Issued 503,845 4.22  Vested (325,057) 5.15  Forfeited (91,956) 4.99  Unvested restricted common stock as of March 31, 2019 622,431 $ 4.72 For the three months ended March 31, 2019 , the total fair value of restricted common stock vested was $ 1,358 . The Company did not receive cash proceeds for any of the restricted common stock issued during the three months ended March 31, 2019 . Stock-Based Compensation The Company recorded stock-based compensation expense related to stock options and restricted stock as follows:     Three Months Ended  March 31,  2019 2018  Cost of product sales and inventories $ 8 $ 31  Research and development 133 170  Selling, general and administrative 2,165 1,183  $ 2,306 $ 1,384 As of March 31, 2019 , the Company had an aggregate of $ 3,780 and $ 2,589 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 2.96 years and 2.34 years, respectively.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2019
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,  2019 2018  Numerator:  Net loss $ (6,787) $ (8,548)  Denominator:  Weighted average shares outstanding, basic and diluted 48,277,129 44,788,068  Net loss per share, basic and diluted $ (0.14) $ (0.19)  Stock options for the purchase of 3,607,219 and 3,254,139 shares of common stock and 622,431 and 809,684 of unvested restricted stock awards were excluded from the computation of diluted net loss per share for the three months ended March 31, 2019 and 2018, respectively, because these stock-based awards had an anti-dilutive impact due to the net loss incurred for the period .

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Taxes [Abstract]
Income Taxes	14. Income Taxes The Company recorded no income tax expense or benefit during the three months ended March 31, 2019 and 201 8 , due to a full valuation allowance recognized against its deferred tax assets.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	15. Leases On January 1, 2019, the Company adopted the ASC 842 using the modified retrospective transition approach by applying the ASC 842 to leases existing at the date of the adoption with no restatement of prior periods or cumulative adjustment to the accumulated deficit . Upon adoption of the ASC 842, the Company elected the package of practical expedients permitted under the ASC 842 transition guidance, which allowed the Company not to reassess prior conclusions related to any expired or existing contracts that are or contain a lease, the lease classification for any expired or existing leases and initial direct lease costs for any existing leases . The Company elected a practical expedient to not separate nonlease components from the associated lease component, therefore, it accounts for the nonlease components together with the associated lease component as a single lease component. Upon adoption of the ASC 842, the Company recognized an operating lease ROU asset of $833 and a corresponding operating lease liability of $890 in th e consolidated balance sheets. The adoption of the ASC 842 did not have an impact on the consolidated statements of operations . Th e operating ROU asset and the corresponding operating lease liability are related to the lease of the Company’s corporate headquarters in Leawood, Kansas . The lease will expire in February 2021 , with an option to extend the lease for two additional consecutive terms of five years, which the Company was not reasonably certain to exercise as of lease inception and, accordingly, this option was not included in the determination of the lease term for the purposes of recognition of the operating lease ROU asset and the operating lease liability. The lease does not contain residual value guarantees or material restrictive covenants by the Company. The annual d iscount rate of approximately 7.3 % was determined to be the incremental borrowing rate as the rate implicit in the lease was not readily determinable. During three months ended March 31, 2019, the Company recognized lease cost of $105 in the consolidated statements of operations in the research and development and selling, general and administrative expenses . During the three months ended March 31, 2019, cash paid for amounts included in the measurement of the operating lease liability was $110 , which was included in the operating cash flows. As of March 31, 2019, the remaining lease term was approximately two years. Future minimum lease payments for operating leases and the present value of lease liabilit y as of March 31, 2019 , are as follows:     Year Ending December 31,  2019 (remaining periods) $ 331  2020 450  2021 75  2022 —  2023 —  Thereafter —  Total lease payments 856  Less: interest (60)  Present value of lease liability $ 796  Under the ASC 840, minimum lease commitments under non-cancelable operating leases for each of the next five years and total thereafter as of December 31, 2018, were as follows:     Year Ending December 31,  2019 $ 441  2020 450  2021 75  2022 —  2023 —  Thereafter —  Total $ 966  

Legal Contingencies

Legal Contingencies	3 Months Ended
	Mar. 31, 2019
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. 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 consolidated 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. 

Agreement and Plan of Merger

Agreement and Plan of Merger	3 Months Ended
	Mar. 31, 2019
Agreement and Plan of Merger [Abstract]
Agreement and Plan of Merger	17. Agreement and Plan of Merger On April 26, 2019, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Elanco and Elanco Athens Inc., a direct wholly owned subsidiary of Elanco (“Acquisition Sub”). Upon the terms and subject to the conditions of the Merger Agreement, Elanco and the Company have agreed that Acquisition Sub will merge with and into the Company, with the Company surviving the merger as a wholly owned subsidiary of Elanco (the “Merger”). Upon completion of the Merger, each share of the Company’s common stock that is outstanding immediately prior to the effective time of the Merger (other than certain excluded shares as described in the Merger Agreement) will automatically be converted into the right to receive (A) 0.1481 validly issued, fully paid and non-assessable share of Elanco common stock, no par value per share , plus (B) one contingent value right representing the right to receive $0.25 in cash if the Company, Elanco or their respective affiliates achieve cumulative net sales of an animal health product that contains capromorelin as an API equal to or exceeding (a) $25,000 during the period beginning on July 1, 2019 and ending on December 31, 2020, or (b) $50,000 during the period beginning on July 1, 2019 and ending on December 31, 2021. The Merger Agreement contains customary representations, warranties and covenants by the Company, Elanco, and Acquisition Sub , and it may be terminated by mutual written consent of Elanco and the Company under certain conditions. The Merger Agreement provides that, upon termination of the Merger Agreement under specified circumstances, including termination of the Merger Agreement by Elanco as a result of an adverse change in the recommendation of the Company’s B oard of D irectors or by the Company in order to enter into a definitive agreement with respect to a Superior Proposal (as such term is defined in the Merger Agreement), the Company may be required to pay Elanco a termination fee of $7,000 . Consummation of the Merger is subject to certain closing conditions, including receipt of the necessary approval by the Company’s stockholders and clearance under the Hart-Scott-Rodino Antitrust Improvements Act, as amended, and other customary closing conditions. The Company’s Board of Directors has unanimously approved the Merger.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policy)	3 Months Ended
	Mar. 31, 2019
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 the development and commercialization of 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, 2018 and the notes thereto in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission ( the “SEC”) on March 1 3 , 201 9 . 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 $248,025 as of March 31, 2019 . 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, 2019 , will be sufficient to fund operations for at least one year from the issuance of these consolidated financial statements. The Company expects continued 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. As a result, if the Company cannot generate sufficient cash flow from operations in the future, the Company will seek to fund its operations through corporate collaborations and licensing arrangements, or other sources, such as public or private equity and further debt financings. 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 US subsidiary and a foreign subsidiary through its dissolution date in December 2018. 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.
Property and Equipment, Net	Property and Equipment, Net Property and equipment is recorded at historical cost, net of accumulated depreciation and amortization of $1,781 and $1,661 , as of March 31, 2019 and December 31, 2018, respectively.
Leases	Leases Effective January 1, 2019, the Company adopted ASC Topic 842 “Leases” ( the “ASC 842”) using the modified retrospective transition approach. Prior to January 1, 2019, the Company recorded leases under ASC Topic 840 “Leases” (the “ASC 840”) . The Company determines if an arrangement is a lease at contract inception. Operating leases are included in operating lease right-of-use (“ROU”) assets, lease liabilities – current portion (included in current liabilities) and lease liabilities (included in long-term liabilities) in the consolidated balance sheet as of March 31, 2019 . Operating lease ROU assets represent the right to use an underlying asset for the lease term and operating lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. The lease term includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit rate when it is readily determinable. If leases do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The Company gives consideration to its prior debt issuances as well as publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates. The lease payments used to determine the operating lease ROU assets may include lease incentives, stated rent increases and escalation clauses linked to rates of inflation when determinable and are recognized in the operating lease assets in the consolidated balance sheets. In addition, lease contracts may contain lease and nonlease components. The Company does not separate nonlease components from their related lease components. The Company excludes short-term leases (term of twelve months or less) from the balance sheet presentation. Lease expense is recognized on a straight-line basis over the lease term.
New Accounting Standards	New Accounting Standards Intangibles – Goodwill and Other – Internal-Use Software In August 2018, the FASB issued guidance that largely aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The guidance provides criteria for determining which implementation costs to capitalize as an asset related to the service contract and which costs to expense. The capitalized implementation costs are required to be expensed over the term of the hosting arrangement. The guidance also clarifies the presentation requirements for reporting such costs in the entity’s financial statements. The guidance is effective for financial statements issued for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. Fair Value Measurements In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance eliminates, modifies and adds disclosure requirements for fair value measurements. The guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently assessing the effect that adoption of this guidance will have on its consolidated financial statements. Compensation – Stock Compensation: Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued guidance that largely aligns the accounting for share-based payment awards issued to employees and nonemployees. Under the new guidance, the existing employee guidance generally will apply to nonemployee share-based transactions, with the exception of specific guidance related to inputs to an option pricing model and the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. In addition, the contractual term will be able to be used in lieu of an expected term in the option-pricing model for nonemployee awards. 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, including in interim periods, but no earlier than an entity’s adoption of ASC 606 . The Company adopted this guidance on January 1, 2019, and the adoption did not have a material impact on its consolidated financial statements.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue [Abstract]
Disaggregation of Revenue by Source	  Three Months Ended  March 31,  2019 2018  Revenues  Licensing and collaboration revenue  GALLIPRANT $ 3,387 $ 1,706  Total licensing and collaboration revenue 3,387 1,706  Product sales  NOCITA $ 2,499 $ 1,547  ENTYCE 1,474 790  Total product sales 3,973 2,337  Total revenues $ 7,360 $ 4,043 

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2019
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, 2019 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,672 $ — $ 9,672 $ — $ 9,672  Short-term investments:  Short-term marketable securities - certificates of deposit 496 — 496 — 496  $ 10,168 $ — $ 10,168 $ — $ 10,168      Fair Value Measurements as of  Carrying December 31, 2018 Using:  Value Level 1 Level 2 Level 3 Total  Assets:  Cash equivalents:  Certificates of deposit $ 9,424 $ — $ 9,424 $ — $ 9,424  Short-term investments:  Short-term marketable securities - certificates of deposit 1,240 — 1,240 — 1,240  $ 10,664 $ — $ 10,664 $ — $ 10,664 

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2019
Investments [Abstract]
Fair Value of Available-for-Sale Marketable Securities	   March 31, 2019  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 496 $ — $ — $ 496  Total $ 496 $ — $ — $ 496      December 31, 2018  Gross Gross  Amortized Unrealized Unrealized Fair  Cost Losses Losses Value  Short-term marketable securities:  Certificates of deposit $ 1,240 $ — $ — $ 1,240  Total $ 1,240 $ — $ — $ 1,240 

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2019
Inventories [Abstract]
Components of Inventories	   March 31, 2019 December 31, 2018  Raw materials $ 121 $ 242  Work-in-process 7,607 8,999  Finished goods 3,100 2,184  $ 10,828 $ 11,425 

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets [Abstract]
Summary of Goodwill	   Gross Impairment Net  Carrying Value Losses Carrying Value  Goodwill $ 40,846 $ — $ 40,846 

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets [Abstract]
Change in the Net Book Value of Intangible Assets	   2019  As of January 1, $ 6,099  Additions 2,000  Amortization expense (143)  Impairment —  As of the end of the period, $ 7,956 
Summary of Amortized Intangible Assets	   Gross Net Weighted  Carrying Accumulated Carrying Average  Value Amortization Value Useful Life  Intellectual property rights for currently marketed products $ 9,000 $ 1,044 $ 7,956 13.6 Years Amortized intangible assets as of December 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 $ 901 $ 6,099 14.1 Years 

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2019
Accrued Expenses and Other Current Liabilities [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	   March 31, 2019 December 31, 2018  Payroll and related expenses $ 1,514 $ 2,587  Professional fees 505 353  Royalty expense 1,712 812  Research and development costs 326 73  Accrued loss on a firm purchase commitment — 72  Other 672 749  Total $ 4,729 $ 4,646 

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	3 Months Ended
	Mar. 31, 2019
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,  2019 2018  Cost of product sales and inventories $ 8 $ 31  Research and development 133 170  Selling, general and administrative 2,165 1,183  $ 2,306 $ 1,384 
2010 Equity Incentive 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, 2018 53,383 $ 4.12 4.10 $ 107  Granted — —  Exercised — —  Forfeited — —  Expired — —  Outstanding as of March 31, 2019 53,383 $ 4.12 3.85 $ 48 
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, 2018 3,114,401 $ 9.86 6.85 $ 2,047  Granted 740,146 4.26  Exercised (8,822) 3.14  Forfeited (226,835) 5.73  Expired (65,054) 7.39  Outstanding as of March 31, 2019 3,553,836 $ 9.02 5.93 $ 160 
Summary of Restricted Stock Activity	   Weighted  Average Grant  Shares Date Fair Value  Unvested restricted common stock as of December 31, 2018 535,599 $ 5.50  Issued 503,845 4.22  Vested (325,057) 5.15  Forfeited (91,956) 4.99  Unvested restricted common stock as of March 31, 2019 622,431 $ 4.72 

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Net Loss Per Share [Abstract]
Schedule of Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders	   Three Months Ended  March 31,  2019 2018  Numerator:  Net loss $ (6,787) $ (8,548)  Denominator:  Weighted average shares outstanding, basic and diluted 48,277,129 44,788,068  Net loss per share, basic and diluted $ (0.14) $ (0.19)  

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of Future Minimum Operating Lease Payments	  Year Ending December 31,  2019 (remaining periods) $ 331  2020 450  2021 75  2022 —  2023 —  Thereafter —  Total lease payments 856  Less: interest (60)  Present value of lease liability $ 796 
Schedule of Minimum Lease Commitments under Non-Cancelable Operating Leases under ASC 840	  Year Ending December 31,  2019 $ 441  2020 450  2021 75  2022 —  2023 —  Thereafter —  Total $ 966 

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Summary of Significant Accounting Policies [Abstract]
Date of incorporation	Dec. 1, 2010
Number of operating segments | segment	1
Accumulated deficit	$ 248,025	$ 241,238
Accumulated depreciation and amortization	$ 1,781	$ 1,661

Revenue (Narrative) (Details)

Revenue (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Line Items]
Accumulated deficit	$ (248,025,000)		$ (241,238,000)
Income tax benefit	0	$ 0
Unsatisfied performance obligations	0
NOCITA and ENTYCE [Member]
Revenue from Contract with Customer [Line Items]
Reserve for product returns and allowances	$ 237,000		$ 222,000

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenue by Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 7,360	$ 4,043
Licensing and Collaboration [Member]
Disaggregation of Revenue [Line Items]
Total revenues	3,387	1,706
Licensing and Collaboration [Member] | GALLIPRANT [Member]
Disaggregation of Revenue [Line Items]
Total revenues	3,387	1,706
Product Sales [Member]
Disaggregation of Revenue [Line Items]
Total revenues	3,973	2,337
Product Sales [Member] | NOCITA [Member]
Disaggregation of Revenue [Line Items]
Total revenues	2,499	1,547
Product Sales [Member] | ENTYCE [Member]
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,474	$ 790

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities (Narrative) (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
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 of Financial Asset_4

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, 2019	Dec. 31, 2018
Assets:
Assets, fair value	$ 10,168	$ 10,664
Carrying Value [Member]
Assets:
Assets, fair value	10,168	10,664
Certificates of Deposit [Member]
Assets:
Cash equivalents	9,672	9,424
Certificates of Deposit [Member] | Carrying Value [Member]
Assets:
Cash equivalents	9,672	9,424
Short-Term Marketable Securities - Certificates of Deposit [Member]
Assets:
Short-term marketable securities - certificates of deposit	496	1,240
Short-Term Marketable Securities - Certificates of Deposit [Member] | Carrying Value [Member]
Assets:
Short-term marketable securities - certificates of deposit	496	1,240
Level 2 [Member]
Assets:
Assets, fair value	10,168	10,664
Level 2 [Member] | Certificates of Deposit [Member]
Assets:
Cash equivalents	9,672	9,424
Level 2 [Member] | Short-Term Marketable Securities - Certificates of Deposit [Member]
Assets:
Short-term marketable securities - certificates of deposit	$ 496	$ 1,240

Investments (Fair Value of Avai

Investments (Fair Value of Available-for-Sale Marketable Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 496	$ 1,240
Fair Value	496	1,240
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	496	1,240
Fair Value	$ 496	$ 1,240

Inventories (Narrative) (Detail

Inventories (Narrative) (Details) $ in Thousands	Mar. 31, 2019USD ($)
Inventories [Abstract]
Non-cancellable open orders	$ 2,094

Inventories (Components of Inve

Inventories (Components of Inventories) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventories [Abstract]
Raw materials	$ 121	$ 242
Work-in-process	7,607	8,999
Finished goods	3,100	2,184
Total	$ 10,828	$ 11,425

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Goodwill and Intangible Assets [Abstract]
Goodwill impairment loss	$ 0

Goodwill (Summary of Goodwill)

Goodwill (Summary of Goodwill) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets [Abstract]
Gross Carrying Value	$ 40,846
Impairment Losses
Net Carrying Value	$ 40,846	$ 40,846

Intangible Assets, Net (Narrati

Intangible Assets, Net (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
Amortization of intangible assets	$ 143	$ 130

Intangible Assets, Net (Change

Intangible Assets, Net (Change in the Net Book Value of Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets [Abstract]
As of January 1,	$ 6,099
Additions	2,000
Amortization expense	(143)	$ (130)
Impairment
As of the end of the period,	$ 7,956

Intangible Assets, Net (Summary

Intangible Assets, Net (Summary of Amortized Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Net carrying value		$ 6,099
Intellectual Property Rights For Currently Marketed Products [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 9,000	7,000
Accumulated amortization	1,044	901
Net carrying value	$ 7,956	$ 6,099
Weighted average useful life	13 years 7 months 6 days	14 years 1 month 6 days

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	Oct. 16, 2015	Mar. 31, 2018
Debt Instrument [Line Items]
Interest expense		$ 853,000
Amortization of debt issuance costs		$ 140,000
Term Loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount	$ 35,000,000
Revolving Line [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 5,000,000
Term Loan And Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate	6.91%
Excess interest rate over prime rate	3.66%

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Schedule of Accrued Expenses and Other Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued expenses:
Payroll and related expenses	$ 1,514	$ 2,587
Professional fees	505	353
Royalty expense	1,712	812
Research and development costs	326	73
Accrued loss on a firm purchase commitment		72
Other	672	749
Total	$ 4,729	$ 4,646

Agreements (RaQualia Pharma Inc

Agreements (RaQualia Pharma Inc Narrative) (Details) - RaQualia Agreements [Member] $ in Thousands	3 Months Ended
	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
Milestones achieved	$ 2,000
GALLIPRANT [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable		$ 2,000
ENTYCE [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable		$ 3,000

Agreements (Pacira Pharmaceutic

Agreements (Pacira Pharmaceuticals, Inc. Narrative) (Details) - USD ($)	Jul. 05, 2018	Mar. 31, 2019
Pacira Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones paid		$ 2,500,000
Accrued milestones		0
Milestones achieved		$ 0
Pacira A&R License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual revenue payment, period delayed	1 year
Pacira A&R License Agreement [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Product completion, pain prevented post-surgery, hours	48 hours
Pacira A&R License Agreement [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Product completion, pain prevented post-surgery, hours	72 hours
Pacira A&R License Agreement [Member] | Commercial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	$ 40,000,000
Initial Tier [Member] | Pacira A&R License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net sales that must be met for milestone payable	50,000,000
Final Tier [Member] | Pacira A&R License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net sales that must be met for milestone payable	$ 250,000,000

Agreements (Elanco GALLIPRANT N

Agreements (Elanco GALLIPRANT Narrative) (Details) - USD ($)	Apr. 22, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenues		$ 7,360,000	$ 4,043,000
Licensing and Collaboration [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenues		3,387,000	$ 1,706,000
Elanco Collaboration Agreement [Member] | Grapiprant Products [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront nonrefundable payment received	$ 45,000,000
Accrued milestones		0
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
Regulatory And Development Milestones [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
Milestones achieved		15,000,000		$ 15,000,000
Reduction for each annual occurrence milestone is not achieved	33.33%
Proceeds from milestones acheived		$ 15,000,000

Agreements (AskAt Inc. Narrativ

Agreements (AskAt Inc. Narrative) (Details) - USD ($)	Feb. 28, 2018	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
In-process research and development				$ 500,000
AskAt Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront option fee			$ 500,000
In-process research and development				500,000
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%
Accrued milestones		$ 0
Milestones paid		0
Royalty payments		$ 0
AskAt Agreement [Member] | Clinical Development And Regulatory Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	$ 3,000,000
AskAt Agreement [Member] | Commercial Milestone [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	12,500,000
AskAt Agreement [Member] | Maximum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestones payable	15,500,000
AskAt Agreement [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net sales that must be met for milestone payable	$ 100,000,000
AskAt Collaboration And Option Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront option fee				$ 500,000

Common Stock (Narrative) (Detai

Common Stock (Narrative) (Details) - USD ($)	May 09, 2019	Dec. 18, 2017	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	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			48,347,297		48,048,914
Treasury stock, shares			129,603		94,107
Treasury stock, value			$ 1,325,000		$ 1,175,000
Restricted stock withheld to satisfy employee tax withholding, shares			35,496	8,688
Restricted stock withheld to satisfy employee tax withholding, per share			$ 4.22	$ 4.90
Proceeds from offering				$ 15,614,000
Value of shares issued				$ 15,498,000
Shelf Registration Statement [Member] | Common Stock [Member]
Class of Stock [Line Items]
Aggregate stock available to sell						$ 100,000,000
At-the-Market Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Aggregate stock available to sell		$ 50,000,000
Percentage of commission on gross proceeds from sale of shares		3.00%
Shares issued				3,383,963
Proceeds from offering				$ 15,498,000
Placement agent fee				483,000
Issuance costs				$ 117,000
Subsequent Event [Member] | At-the-Market Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Value of shares issued	$ 24,852,000
2013 Plan [Member]
Class of Stock [Line Items]
Unvested restricted common stock outstanding			622,431		535,599

Stock-Based Awards (Narrative)

Stock-Based Awards (Narrative) (Details) - USD ($)	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from stock option exercises		$ 27,000	$ 5,000
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		2,173,138		2,173,138
Stock options granted		740,146
Annual increase in shares	1,203,369
Unrecognized stock-based compensation expense for options outstanding		$ 3,780,000		$ 3,780,000
Unrecognized stock-based compensation expense, other than options		2,589,000		$ 2,589,000
2013 Plan [Member] | Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised		9,000
Proceeds from stock option exercises		$ 27,000
Weighted average grant date fair value of options granted		$ 2.68
Unrecognized stock-based compensation expense, recognition period		2 years 11 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		$ 1,358,000
Proceeds from the issuance of restricted stock		$ 0
Unrecognized stock-based compensation expense, recognition period		2 years 4 months 2 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, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / 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, 2018 | shares	53,383
Shares Issuable Under Options, Outstanding as of March 31, 2019 | shares	53,383	53,383
Weighted Average Exercise Price, Outstanding as of December 31, 2018 | $ / shares	$ 4.12
Weighted Average Exercise Price, Outstanding as of March 31, 2019 | $ / shares	$ 4.12	$ 4.12
Weighted Average Remaining Contractual Term, Outstanding	3 years 10 months 6 days	4 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding | $	$ 48	$ 107
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issuable Under Options, Outstanding as of December 31, 2018 | shares	3,114,401
Shares Issuable Under Options, Granted | shares	740,146
Shares Issuable Under Options, Exercised | shares	(8,822)
Shares Issuable Under Options, Forfeited | shares	(226,835)
Shares Issuable Under Options, Expired | shares	(65,054)
Shares Issuable Under Options, Outstanding as of March 31, 2019 | shares	3,553,836	3,114,401
Weighted Average Exercise Price, Outstanding as of December 31, 2018 | $ / shares	$ 9.86
Weighted Average Exercise Price, Granted | $ / shares	4.26
Weighted Average Exercise Price, Exercised | $ / shares	3.14
Weighted Average Exercise Price, Forfeited | $ / shares	5.73
Weighted Average Exercise Price, Expired | $ / shares	7.39
Weighted Average Exercise Price, Outstanding as of March 31, 2019 | $ / shares	$ 9.02	$ 9.86
Weighted Average Remaining Contractual Term, Outstanding	5 years 11 months 5 days	6 years 10 months 6 days
Aggregate Intrinsic Value, Outstanding | $	$ 160	$ 2,047

Stock-Based Awards (Summary o_2

Stock-Based Awards (Summary of Restricted Stock Activity) (Details) - 2013 Plan [Member]	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted common stock as of December 31, 2018, Shares | shares	535,599
Issued, Shares | shares	503,845
Vested, Shares | shares	(325,057)
Forfeited, Shares | shares	(91,956)
Unvested restricted common stock as of March 31, 2019, Shares | shares	622,431
Unvested restricted common stock as of December 31, 2018, Weighted Average Grant Date Fair Value | $ / shares	$ 5.50
Issued, Weighted Average Grant Date Fair Value | $ / shares	4.22
Vested, Weighted Average Grant Date Fair Value | $ / shares	5.15
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	4.99
Unvested restricted common stock as of March 31, 2019, Weighted Average Grant Date Fair Value | $ / shares	$ 4.72

Stock-Based Awards (Summary o_3

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, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,306	$ 1,384
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	133	170
Cost of Product Sales and Inventories [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	8	31
Selling, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,165	$ 1,183

Net Loss Per Share (Narrative)

Net Loss Per Share (Narrative) (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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	3,607,219	3,254,139
Unvested Restricted Stock [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	622,431	809,684

Net Loss Per Share (Schedule of

Net Loss Per Share (Schedule of Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net loss	$ (6,787)	$ (8,548)
Denominator:
Weighted average shares outstanding, basic and diluted	48,277,129	44,788,068
Net loss per share, basic and diluted	$ (0.14)	$ (0.19)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Taxes [Abstract]
Income tax expense (benefit)	$ 0	$ 0

Leases (Narrative) (Details)

Leases (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)item	Jan. 01, 2019USD ($)
Leases [Abstract]
Operating lease right-of-use asset	$ 744	$ 833
Lease liability	$ 796	$ 890
Operating lease expiration date	Feb. 28, 2021
Option to extend, number of additional consecutive terms | item	2
Renewal term	5 years
Weighted average discount rate	7.30%
Lease cost	$ 105
Cash paid for operating lease liabilities	$ 110
Weighted average remaining lease term	2 years

Leases (Schedule of Future Mini

Leases (Schedule of Future Minimum Operating Lease Payments) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Leases [Abstract]
2019 (remaining periods)	$ 331
2020	450
2021	75
2022
2023
Thereafter
Total lease payments	856
Less: interest	(60)
Present value of lease liability	$ 796	$ 890

Leases (Schedule of Minimum Lea

Leases (Schedule of Minimum Lease Commitments under Non-Cancelable Operating Leases under ASC 840) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 441
2020	450
2021	75
Total	$ 966

Agreement and Plan of Merger (N

Agreement and Plan of Merger (Narrative) (Details) - Subsequent Event [Member] $ / shares in Units, $ in Thousands	Apr. 26, 2019USD ($)$ / sharesitemshares
Business Acquisition [Line Items]
Number of shares each share will convert to under merger | shares	0.1481
Contingent value right awarded per share | item	1
Continge value right per share amount if specified achievement reached | $ / shares	$ 0.25
Termination fee	$ 7,000
Beginning on July 1, 2019 and Ending on December 31, 2020 [Member]
Business Acquisition [Line Items]
Contingent value right threshold	25,000
Beginning on July 1, 2019 and Ending on December 31, 2021 [Member]
Business Acquisition [Line Items]
Contingent value right threshold	$ 50,000
Elanco Animal Health, Inc. [Member]
Business Acquisition [Line Items]
Common stock, no par value | $ / shares	$ 0