Chimerix (CMRX) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Registrant Name	CHIMERIX INC
Entity Central Index Key	0001117480
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		61,270,268

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 21,644	$ 81,106
Short-term investments, available-for-sale	136,755	105,424
Accounts receivable	774	330
Prepaid expenses and other current assets	2,200	2,598
Total current assets	161,373	189,458
Property and equipment, net of accumulated depreciation	1,054	1,210
Operating lease right-of-use assets	969
Other long-term assets	45	46
Total assets	163,441	190,714
Current liabilities:
Accounts payable	1,832	4,691
Accrued liabilities	11,954	8,275
Total current liabilities	13,786	12,966
Lease-related obligations	537	144
Total liabilities	14,323	13,110
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized at June 30, 2019 and December 31, 2018; no shares issued and outstanding as of June 30, 2019 and December 31, 2018	0	0
Common stock, $0.001 par value, 200,000,000 shares authorized at June 30, 2019 and December 31, 2018; 51,230,916 and 50,735,279 shares issued and outstanding as of June 30, 2019 and December 31, 2018, respectively	51	51
Additional paid-in capital	740,547	733,907
Accumulated other comprehensive gain (loss), net	125	(92)
Accumulated deficit	(591,605)	(556,262)
Total stockholders’ equity	149,118	177,604
Total liabilities and stockholders’ equity	$ 163,441	$ 190,714

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Contract revenue	$ 1,438	$ 1,193	$ 3,794	$ 1,983
Operating expenses:
Research and development	13,827	13,712	27,342	28,071
General and administrative	6,312	6,650	13,998	13,388
Total operating expenses	20,139	20,362	41,340	41,459
Loss from operations	(18,701)	(19,169)	(37,546)	(39,476)
Other (expense) income:
Unrealized loss on equity investment	(22)	(78)	(30)	(212)
Interest income and other, net	1,073	634	2,233	1,249
Net loss	(17,650)	(18,613)	(35,343)	(38,439)
Other comprehensive loss:
Unrealized gain on debt investments, net	77	225	217	122
Comprehensive loss	$ (17,573)	$ (18,388)	$ (35,126)	$ (38,317)
Per share information:
Net loss, basic and diluted (in dollars per share)	$ (0.35)	$ (0.39)	$ (0.69)	$ (0.81)
Weighted-average shares outstanding, basic and diluted (in shares)	51,130,104	47,811,552	51,009,935	47,725,209

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	51,230,916	50,735,279
Common stock, shares outstanding (in shares)	51,230,916	50,735,279

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2017	$ 221,810	$ 47	$ 709,514	$ (963)	$ (486,788)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,392	1	3,391
Exercise of stock options	60		60
Employee stock purchase plan purchases	358		358
Comprehensive loss:
Unrealized gain on debt investments, net	(103)			(103)
Net loss	(19,826)				(19,826)
Total comprehensive loss	(19,929)
Ending Balance at Mar. 31, 2018	205,691	48	713,323	(1,066)	(506,614)
Beginning Balance at Dec. 31, 2017	221,810	47	709,514	(963)	(486,788)
Comprehensive loss:
Unrealized gain on debt investments, net	122
Total comprehensive loss	(38,317)
Ending Balance at Jun. 30, 2018	191,393	48	717,413	(841)	(525,227)
Beginning Balance at Mar. 31, 2018	205,691	48	713,323	(1,066)	(506,614)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	4,035	0	4,035
Exercise of stock options	55		55
Employee stock purchase plan purchases	0		0
Comprehensive loss:
Unrealized gain on debt investments, net	225			225
Net loss	(18,613)				(18,613)
Total comprehensive loss	(18,388)
Ending Balance at Jun. 30, 2018	191,393	48	717,413	(841)	(525,227)
Beginning Balance at Dec. 31, 2018	177,604	51	733,907	(92)	(556,262)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	4,073		4,073
Exercise of stock options	13		13
Employee stock purchase plan purchases	170		170
Comprehensive loss:
Unrealized gain on debt investments, net	140			140
Net loss	(17,693)				(17,693)
Total comprehensive loss	(17,553)
Ending Balance at Mar. 31, 2019	164,307	51	738,163	48	(573,955)
Beginning Balance at Dec. 31, 2018	177,604	51	733,907	(92)	(556,262)
Comprehensive loss:
Unrealized gain on debt investments, net	217
Total comprehensive loss	(35,126)
Ending Balance at Jun. 30, 2019	149,118	51	740,547	125	(591,605)
Beginning Balance at Mar. 31, 2019	164,307	51	738,163	48	(573,955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	2,367		2,367
Exercise of stock options	17		17
Employee stock purchase plan purchases	0		0
Comprehensive loss:
Unrealized gain on debt investments, net	77			77
Net loss	(17,650)				(17,650)
Total comprehensive loss	(17,573)
Ending Balance at Jun. 30, 2019	$ 149,118	$ 51	$ 740,547	$ 125	$ (591,605)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net loss	$ (35,343)	$ (38,439)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	306	487
Amortization of discount/premium on investments	(1,205)	(171)
Share-based compensation	6,440	7,427
Unrealized loss on equity investment	30	212
Lease-related amortization	(36)	(24)
Changes in operating assets and liabilities:
Accounts receivable	(444)	1,463
Prepaid expenses and other assets	399	24
Accounts payable and accrued liabilities	302	(3,529)
Net cash used in operating activities	(29,551)	(32,550)
Cash flows from investing activities:
Purchases of property and equipment	(150)	(96)
Purchases of short-term investments	(107,149)	(18,117)
Purchases of long-term investments	0	(6,031)
Proceeds from sales of short-term investments	0	22,000
Proceeds from maturities of short-term investments	77,210	43,500
Net cash (used in) provided by investing activities	(30,089)	41,256
Cash flows from financing activities:
Proceeds from exercise of stock options	30	115
Proceeds from employee stock purchase plan	171	358
Payments of deferred offering costs	(23)	(280)
Net cash provided by financing activities	178	193
Net (decrease) increase in cash and cash equivalents	(59,462)	8,899
Cash and cash equivalents:
Beginning of period	81,106	18,548
End of period	$ 21,644	$ 27,447

The Business and Summary of Sig

The Business and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
The Business and Summary of Significant Accounting Policies	The Business and Summary of Significant Accounting Policies Description of Business Chimerix, Inc. (the Company) is a biopharmaceutical company dedicated to accelerating the advancement of innovative medicines that make a meaningful impact in the lives of patients living with cancer and other serious diseases. The Company is developing CX-01 (dociparstat sodium), an investigational product, targeting multiple proteins involved in cancer cell resistance to chemotherapy, for the treatment of acute myeloid leukemia (AML) and other hematologic malignancies. The Company is also developing brincidofovir (BCV or CMX001), an anti-viral drug candidate, as a medical countermeasure for smallpox. Basis of Presentation The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Company’s audited financial statements and notes thereto included in its Annual Report on Form 10-K for the year ended December 31, 2018 . In the opinion of the Company’s management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of its financial position, operating results and cash flows for the periods presented have been included. Operating results for the three and six months ended June 30, 2019 are not necessarily indicative of the results that may be expected for the full year, for any other interim period or for any future year. Fair Value of Financial Instruments The carrying amounts of certain financial instruments, including accounts receivable, accounts payable and accrued expenses approximate their fair values due to the short-term nature of such instruments. For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data are based primarily upon estimates and are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, fair value measurements cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the calculated current or future fair values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The determination of where an asset or liability falls in the hierarchy requires significant judgment. These levels are: • Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2 — Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and models for which all significant inputs are observable, either directly or indirectly. • Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement. At June 30, 2019 , the Company had cash equivalents including money market accounts, and at December 31, 2018 , the Company had cash equivalents including money market accounts and U.S. Treasury securities, whose value is based on using quoted market prices. At June 30, 2019 and December 31, 2018 , the Company had short-term investments including U.S. Treasury securities, whose value is based on using quoted market prices. Accordingly, these securities are classified as Level 1. At June 30, 2019 and December 31, 2018 , the Company had short-term investments including stock of a U.S. corporation. The Company's investment in ContraVir Pharmaceuticals (ContraVir) common stock was categorized as a Level 1 asset and had a value based on ContraVir's common stock value at June 30, 2019 and December 31, 2018 . For the three months ended June 30, 2019 and 2018 , the Company recorded an unrealized loss related to the Company's investment in ContraVir common stock of approximately $22,000 and $78,000 , respectively, and for the six months ended June 30, 2019 and 2018 , the Company recorded an unrealized loss related to the Company's investments in ContraVir common stock of approximately $30,000 and $212,000 , respectively, which was recognized in unrealized loss on equity investment in the Consolidated Statements of Operations and Comprehensive Loss. At June 30, 2019 , the Company had cash equivalents including commercial paper and short-term investments including commercial paper and corporate bonds. At December 31, 2018 , the Company had cash equivalents including commercial paper and corporate bonds, and short-term investments including commercial paper and corporate bonds. As quoted prices are not available for these securities, they are valued using independent pricing models or other model-based valuation techniques such as the present value of future cash flows, adjusted for the security’s credit rating, prepayment assumptions and other factors such as credit loss assumptions. Accordingly, these securities are classified as Level 2. There was no material re-measurement to fair value of financial assets and liabilities that are not measured at fair value on a recurring basis. For additional information regarding the Company's investments, please refer to Note 2, "Investments." Below are tables that present information about certain assets measured at fair value on a recurring basis (in thousands): Fair Value Measurements June 30, 2019 Total Quoted Prices in Significant Other Significant Cash equivalents Money market funds $ 11,906 $ 11,906 $ — $ — Commercial paper 5,835 — 5,835 — Total cash equivalents 17,741 11,906 5,835 — Short-term investments U.S. treasury securities 38,405 38,405 — — Common stock of U.S. corporation 8 8 — — Commercial paper 45,673 — 45,673 — Corporate bonds 52,669 — 52,669 — Total short-term investments 136,755 38,413 98,342 — Total assets $ 154,496 $ 50,319 $ 104,177 $ — Fair Value Measurements December 31, 2018 Total Quoted Prices in Significant Other Significant Cash equivalents Money market funds $ 30,726 $ 30,726 $ — $ — U.S. treasury securities 11,482 11,482 — — Commercial paper 29,677 — 29,677 — Corporate bonds 4,008 — 4,008 — Total cash equivalents 75,893 42,208 33,685 — Short-term investments U.S. treasury securities 12,589 12,589 — — Common stock of U.S. corporation 38 38 — — Commercial paper 60,114 — 60,114 — Corporate bonds 32,683 — 32,683 — Total short-term investments 105,424 12,627 92,797 — Total assets $ 181,317 $ 54,835 $ 126,482 $ — Accrued Liabilities Accrued liabilities consisted of the following (in thousands): June 30, 2019 December 31, 2018 Accrued research and development expenses $ 6,378 $ 4,525 Accrued compensation 4,154 2,469 Other accrued liabilities 1,422 1,281 Total accrued liabilities $ 11,954 $ 8,275 Revenue Recognition Policy The Company’s revenues generally consist of (i) contract revenue - revenue generated under federal contracts, and (ii) collaboration and licensing revenue - revenue related to non-refundable upfront fees, royalties and milestone payments earned under license agreements. Revenue is recognized in accordance with the criteria outlined in Accounting Standards Codification (ASC) 606 issued by the Financial Accounting Standards Board (FASB). Following this accounting pronouncement, a five-step approach is applied for recognizing revenue, including (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. Biomedical Advanced Research and Development Authority (BARDA) In February 2011, the Company entered into a contract with BARDA for the advanced development of brincidofovir as a medical countermeasure in the event of a smallpox release. Under the contract, the Company may receive up to $75.8 million in expense reimbursement and $5.3 million in fees over the performance of 1 base segment and 4 option segments. Exercise of each option segment is solely at the discretion of BARDA. Currently, option segments 1 through 3 have been exercised. The Company assessed the services in accordance with the authoritative guidance and concluded that there is a potential of 5 separate contracts ( 1 base segment and 4 option segments) within this agreement, each of which has a single performance obligation. The transaction price for each segment, based on the transaction price as defined in each segment contract, is allocated to the single performance obligation for each contract. The transaction price is recognized over time by measuring the progress toward complete satisfaction of the performance obligation. The progress toward complete satisfaction is estimated based on the costs incurred to date relative to the total estimated costs per the terms of each contract. The Company typically invoices BARDA monthly as costs are incurred. The base segment and first option segment were completed prior to adoption of ASC 606. The Company is currently performing under the second and third option segments of the contract during which the Company may receive up to a total of $23.9 million and $14.1 million in expense reimbursement and fees, respectively. The second option and third option segments are scheduled to end on May 31, 2020. ContraVir Pharmaceuticals The Company entered into a license agreement with ContraVir on December 17, 2014 for the development and commercialization of CMX157 for certain antiviral indications. The Company assessed the agreement in accordance with the authoritative guidance and concluded that the ContraVir contract includes multiple performance obligations, which had all been satisfied in 2015 prior to the adoption of ASC 606. The ContraVir contract has one fixed and several variable transaction amounts. The fixed fee portion of the contract was for the license to CMX157 rights. The Company recognized revenue for the fixed fee portion of the contract in 2015 when the performance obligations were satisfied. The license agreement was terminated effective June 1, 2019. In July 2019, ContraVir changed its name to Hepion Pharmaceuticals, Inc. Research and Development Prepaids and Accruals As part of the process of preparing financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines prepaid and accrual estimates through discussion with applicable personnel and outside service providers as to the progress or state of communication of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its prepaid and accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2019 , there had been no material adjustments to the Company’s prior period estimates of prepaid and accruals for research and development expenses. The Company’s research and development prepaids and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights. Diluted net loss per share of common stock is computed by dividing net loss by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of warrants to purchase common stock, non-vested restricted stock, stock options, and employee stock purchase plan purchase rights outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during the periods of net loss, there was no difference between basic and diluted loss per share of common stock for the three and six months ended June 30, 2019 and 2018 . Impact of Recently Issued Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which amends the impairment model by requiring entities to use a forward-looking approach on expected losses to estimate credit losses on certain financial instruments, including trade receivables and available-for-sale debt securities. The new guidance will be effective for the Company beginning in the first quarter of 2020, with early adoption permitted. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. Impact of Recently Adopted Accounting Standards In February 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-02, “Leases (Topic 842)”, which has been amended through subsequent ASUs, and which increases transparency and comparability among companies accounting for lease transactions. The most significant change of this update requires the recognition of lease assets and liabilities on the balance sheet for lessees for operating lease arrangements with lease terms greater than 12 months. This ASU is effective for financial statements issued for annual periods and interim periods within those annual periods, beginning after December 15, 2018. The Company adopted this standard effective January 1, 2019 using the alternative modified retrospective adoption method allowed by ASU 2018-11. The Company elected to use the package of three practical expedients which allows the Company not to reassess whether contracts are or contain leases, lease classification, and whether initial direct costs qualify for capitalization. The Company has completed its assessment of the impact of the standard and determined that the only material leases that the Company holds are real estate operating leases. Upon adoption of the standard, the Company recorded a right of use asset of $1.4 million and lease liability of $1.6 million on its consolidated balance sheets with no adjustment to beginning retained earnings in the period of adoption.

Investments

Investments	6 Months Ended
	Jun. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The following tables summarize the Company's debt investments (in thousands): June 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate bonds $ 52,595 $ 74 $ — $ 52,669 U.S. treasury securities 38,379 27 (1 ) 38,405 Commercial paper 45,649 25 (1 ) 45,673 Total investments $ 136,623 $ 126 $ (2 ) $ 136,747 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate bonds $ 32,724 $ — $ (41 ) $ 32,683 Commercial paper 60,159 — (45 ) 60,114 U.S. treasury securities 12,592 — (3 ) 12,589 Total investments $ 105,475 $ — $ (89 ) $ 105,386 The following tables summarize the Company's debt investments with unrealized losses, aggregated by investment type and the length of time that individual investments have been in a continuous unrealized loss position (in thousands, except number of securities): June 30, 2019 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Commercial paper $ 6,955 $ (1 ) $ — $ — $ 6,955 $ (1 ) U.S. treasury securities 9,980 (1 ) — — 9,980 (1 ) Total $ 16,935 $ (2 ) $ — $ — $ 16,935 $ (2 ) Number of securities with unrealized losses 4 — 4 December 31, 2018 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate bonds $ 32,683 $ (41 ) $ — $ — $ 32,683 $ (41 ) Commercial paper 60,114 (45 ) — — 60,114 (45 ) U.S. treasury securities 12,589 (3 ) — — 12,589 (3 ) Total $ 105,386 $ (89 ) $ — $ — $ 105,386 $ (89 ) Number of securities with unrealized losses 36 — 36 The Company periodically reviews available-for-sale securities for other-than-temporary declines in fair value below the cost basis and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company evaluates, among other things, the duration and extent to which the fair value of a security is less than its cost; the financial condition of the issuer and any changes thereto; and the Company’s intent to sell, or whether it will more likely than not be required to sell, the security before recovery of its cost basis. At June 30, 2019 , the Company did not intend to sell, and was not more likely than not to be required to sell, the available-for-sale debt securities in an unrealized loss position before recovery of the cost basis of the securities, which may be at maturity. There were no such declines in value for the three and six months ended June 30, 2019 and 2018 . Unrealized gains and losses on debt investments are recorded to unrealized gain (loss) on investments, net in the Consolidated Statements of Operations and Comprehensive Loss. The Company recognizes interest income on an accrual basis in interest income in the Consolidated Statements of Operations and Comprehensive Loss. The following table summarizes the scheduled maturity for the Company's debt investments at June 30, 2019 (in thousands): Maturing in one year or less $ 136,747 Maturing after one year through two years — Total debt investments 136,747 Common stock of U.S. corporation 8 Total investments $ 136,755

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company leases its facilities under long-term operating leases that expire at various dates through 2021. The Company generally has options to renew lease terms on its facilities, which may be exercised at the Company's sole discretion. In addition, certain lease arrangements may be terminated prior to their original expiration date at the Company's discretion. The Company evaluates renewal and termination options at the lease commencement date to determine if it is reasonably certain to exercise the option and have concluded on all operating leases that it is not reasonably certain that any options will be exercised. The weighted-average remaining lease term for the Company's operating leases as of June 30, 2019 was 1.75 years . Expense related to leases is recorded on a straight-line basis over the lease term. Lease expense under operating leases, including common area maintenance fees, totaled approximately $182,000 and $181,000 , respectively, for the three months ended June 30, 2019 and 2018 , and $376,000 and $351,000 for the six months ended June 30, 2019 and 2018 , respectively. The discount rate implicit within the Company's leases is generally not determinable and therefore the Company determines the discount rate based on its incremental borrowing rate based on the information available at commencement date. As of June 30, 2019 , the operating lease liabilities reflect a weighted-average discount rate of 13.07% . The following table sets forth the operating lease right-of-use assets and liabilities as of June 30, 2019 (in thousands): Assets Operating Lease Right-of-Use Assets $ 969 Liabilities Operating Lease Short-term Liabilities (recorded within Accrued liabilities) $ 618 Operating Lease Long-term Liabilities (recorded within Lease-related obligations) 519 Total Operating Lease Liabilities $ 1,137 Operating lease payments over the remainder of the lease terms are as follows (in thousands): Years Ending December 31, As of June 30, 2019 2019 $ 365 2020 719 2021 182 Total future minimum rental payments $ 1,266 Less amount of lease payments representing interest 129 Total present value of lease payments $ 1,137 As of December 31, 2018 , future minimum payments under operating leases under ASC 840 were as follows (in thousands): Years Ending December 31, As of December 31, 2018 2019 $ 786 2020 797 2021 235 Total future minimum rental payments $ 1,818 For the three months ended June 30, 2019 and 2018 , the Company made lease payments of approximately $194,000 and $186,000 , respectively, and for the six months ended June 30, 2019 and 2018 , the Company made lease payments of approximately $386,000 and $370,000 , respectively, which are included in operating cash flows. Sublease The Company subleases 3,537 square feet of its office space under a non-cancelable operating lease that expires in February 2021. For the three and six months ended June 30, 2019 , the Company recognized approximately $18,000 and $35,000 of income in Interest income and other, net on the Consolidated Statement of Operations and Comprehensive Loss. For the three and six months ended June 30, 2018 , the Company recognized approximately $18,000 and $35,000 of a reduction of rent expense in operating expenses on the Consolidated Statement of Operations and Comprehensive Loss. Total future minimum rentals under the non-cancelable operating sublease are presented below (in thousands): Years Ending December 31, As of June 30, 2019 2019 $ 39 2020 81 2021 14 Total future minimum sublease rentals $ 134 Significance of Revenue Source The Company is the recipient of federal research contract funds from BARDA, the sole source of the Company's contract revenue. Periodic audits are required under the Company’s BARDA agreement and certain costs may be questioned as appropriate under the BARDA agreement. Management believes that such amounts in the current year, if any, are not significant. Accordingly, no provision for refundable amounts under the BARDA agreement had been made as of June 30, 2019 and December 31, 2018 .

Equity Transactions and Share-b

Equity Transactions and Share-based Compensation	6 Months Ended
	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Equity Transactions and Share-based Compensation	Equity Transactions and Share-based Compensation Stock Options In connection with the Company’s IPO, the Company adopted the 2013 Equity Incentive Plan (the 2013 Plan). The 2013 Plan provides for the grant of incentive stock options (ISOs), non-statutory stock options (NSOs), stock appreciation rights, restricted stock awards, restricted stock unit (RSU) awards, performance-based stock awards, and other forms of equity compensation (collectively, stock awards), all of which may be granted to employees, including officers, non-employee directors and consultants of the Company and its affiliates. Additionally, the 2013 Plan provides for the grant of performance cash awards. The number of shares of common stock reserved for future issuance automatically increases on January 1 of each calendar year by 4% of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s board of directors. On January 1, 2019 , the common stock reserved for issuance under the 2013 Plan was automatically increased by 2.0 million shares. As of June 30, 2019 , there was a total of 2.3 million shares reserved for future issuance under the 2013 Plan. The Company issued approximately 6,000 and 14,000 shares of common stock pursuant to the exercise of stock options during the three and six months ended June 30, 2019 , respectively. Employee Stock Purchase Plan In February 2013, the Company’s board of directors adopted the 2013 Employee Stock Purchase Plan (ESPP), which was subsequently ratified by stockholders and became effective in April 2013. Initially, the ESPP authorized the issuance of 704,225 shares of common stock pursuant to purchase rights granted to the Company’s employees or to employees of any of its designated affiliates. The number of shares of common stock reserved for issuance automatically increases on January 1 of each calendar year, from January 1, 2014 through January 1, 2023 by the lesser of (a) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, (b) 422,535 shares, or (c) a number determined by the Company’s board of directors that is less than (a) and (b). On January 1, 2019 , the common stock reserved for issuance under the ESPP was automatically increased by an additional 422,535 shares. The Company has reserved a total of 3.1 million shares of common stock to be purchased under the ESPP, of which 2.4 million shares remained available for purchase as of June 30, 2019 . The ESPP provides for an automatic reset feature to start participants on a new twenty-four month participation period in the event that the common stock market value on a purchase date is less than the common stock value on the first day of the twenty-four month offering period. Eligible employees may authorize an amount up to 15% of their salary to purchase common stock at the lower of a 15% discount to the beginning price of their offering period or a 15% discount to the ending price of each six-month purchase interval. The Company issued no shares of common stock pursuant to the ESPP during the three months ended June 30, 2019 . The Company issued approximately 113,000 shares of common stock pursuant to the ESPP during the six months ended June 30, 2019 . Compensation expense for shares purchased under the ESPP related to the purchase discount and the “look-back” option and were determined using a Black-Scholes option pricing model. Restricted Stock Units The Company has issued RSUs to certain employees which vest based on service criteria. When vested, the RSU represents the right to be issued the number of shares of the Company's common stock that is equal to the number of RSUs granted. The grant date fair value for RSUs is based upon the market price of the Company's common stock on the date of the grant. The fair value is then amortized to compensation expense over the requisite service period or vesting term. The Company issued approximately 201,000 and 369,000 shares of common stock pursuant to the vesting of RSUs during the three and six months ended June 30, 2019 , respectively. Stock-based Compensation For awards with only service conditions and graded-vesting features, the Company recognizes compensation expense on a straight-line basis over the requisite service period. Total share-based compensation expense recognized related to stock options, the ESPP and RSUs was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development expense $ 1,000 $ 1,536 $ 2,270 $ 2,856 General and administrative expense 1,367 2,500 4,170 4,571 Total share-based compensation expense $ 2,367 $ 4,036 $ 6,440 $ 7,427 On February 5, 2019, Dr. M. Michelle Berrey, the Company's then President and Chief Executive Officer, resigned. The Company entered into a severance agreement with Dr. Berrey that provides for severance benefits to her in connection with her resignation. Among other benefits, Dr. Berrey received accelerated vesting of her outstanding stock options and RSUs as if she had continued service for an additional 15 month period. In addition, Dr. Berrey's vested options were modified to extend her exercise period to May 5, 2020. The Company recorded a charge of $1.8 million to compensation expense on the date of her resignation related to the acceleration of vesting and the modifications of her outstanding stock options and RSUs. In April 2019, the Company granted stock options covering a total of 1,750,000 shares in connection with the hiring of its Chief Executive Officer and Chief Business Officer. These grants were non-qualified stock options, have a 10 -year term and will vest over four years , with one-fourth vesting on the one-year anniversary of the grant date and remaining three-fourths vesting over the following three years in equal monthly installments. These stock options are subject to the terms of the Company's 2013 Equity Incentive Plan, but were granted outside of the 2013 Equity Incentive Plan, as they constituted inducement grants in accordance with Nasdaq Stock Market rules. In May 2019, related to the Company’s reduction in workforce further discussed in Note 7, certain outstanding stock option and RSU grants received accelerated vesting as if the service period of the terminated employee continued for an additional 12 month period. In addition, certain vested options were modified to extend their exercise period for 12 months. The Company recorded a charge of $0.7 million to compensation expense on the date of the reduction in workforce related to the acceleration of vesting and the modifications of the outstanding stock options and RSUs.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company estimates an annual effective tax rate of 0% for the year ending December 31, 2019 as the Company incurred losses for the six month period ended June 30, 2019 and is forecasting additional losses through the fourth quarter, resulting in an estimated net loss for both financial statement and tax purposes for the year ending December 31, 2019 . Therefore, no federal or state income taxes are expected and none have been recorded at this time. Income taxes have been accounted for using the liability method in accordance with FASB ASC 740. Due to the Company's history of losses since inception, there is not enough evidence at this time to support that the Company will generate future income of a sufficient amount and nature to utilize the benefits of its net deferred tax assets. Accordingly, the deferred tax assets have been reduced by a full valuation allowance, since the Company does not currently believe that realization of its deferred tax assets is more likely than not. At June 30, 2019 , the Company had no unrecognized tax benefits that would reduce the Company’s effective tax rate if recognized.

Significant Agreements

Significant Agreements	6 Months Ended
	Jun. 30, 2019
Revenue Recognition [Abstract]
Significant Agreements	Significant Agreements The Regents of the University of California In May 2002, the Company entered into a license agreement with The Regents of the University of California (UC) under which the Company obtained an exclusive, worldwide license to UC’s patent rights in certain inventions (the UC Patent Rights) related to lipid-conjugated antiviral compounds and their use, including certain patents relating to brincidofovir. On July 1, 2019, the Company provided a notice of termination of the license agreement effective September 29, 2019. The termination of the license to the UC Patent Rights does not affect the Chimerix solely-owned patents covering CMX001/brincidofovir composition of matter that currently are set to expire in 2034. Biomedical Advanced Research and Development Authority (BARDA) In February 2011, the Company entered into a contract with BARDA for the advanced development of brincidofovir as a medical countermeasure in the event of a smallpox release. Under the contract, BARDA will reimburse the Company, plus pay a fixed fee, for the research and development of brincidofovir as a broad-spectrum therapeutic antiviral for the treatment of smallpox infections. The contract consists of an initial performance period, referred to as the base performance segment, plus up to four extension periods, referred to as option segments, each of which may be exercised at BARDA’s sole discretion. The Company must complete the agreed upon milestones and deliverables in each discrete work segment before the next option segment is eligible to be exercised. Under the contract as currently in effect, the Company may receive up to $75.8 million in expense reimbursement and $5.3 million in fees. The Company is currently performing under the second and third option segments of the contract during which the Company may receive up to a total of $23.9 million and $14.1 million in expense reimbursement and fees, respectively. The second and third option segments are scheduled to end on May 31, 2020. Of the $75.8 million in expense reimbursement and $5.3 million in fees that the Company may receive, approximately $74.3 million in expense reimbursement and fees has been funded. As of June 30, 2019 , of the total funding the Company had invoiced an aggregate of $66.3 million with respect to the base performance segment and the first three option segments. For the three months ended June 30, 2019 and 2018 , the Company recognized revenue under this contract of $1.4 million and $1.2 million , respectively, and for the six months ended June 30, 2019 and 2018 , the Company recognized revenue under this contract of $3.8 million and $2.0 million , respectively. ContraVir Pharmaceuticals On December 17, 2014, the Company entered into a license agreement with ContraVir (Nasdaq:CTRV) for the development and commercialization of CMX157 for certain antiviral indications. Under the terms of the agreement, ContraVir has sole responsibility with respect to the control of the development and commercialization of CMX157. In exchange for the license to CMX157 rights, the Company received an upfront payment consisting of ContraVir Series B Convertible Preferred Stock which the Company converted into shares of ContraVir common stock in 2016. As of June 30, 2019 and December 31, 2018 , the fair value of the investment was recorded as a short-term investment of approximately $8,000 and $38,000 , respectively. The license agreement was terminated effective June 1, 2019. In July 2019, ContraVir changed its name to Hepion Pharmaceuticals, Inc. University of Michigan In 2006, the Company entered into a license agreement with The Regents of the University of Michigan (UM) under which the Company obtained an exclusive, worldwide license to UM’s patent rights in certain inventions (UM Patent Rights) related to certain compounds originally synthesized at UM. Under the license agreement, the Company is permitted to research, develop, manufacture and commercialize products utilizing the UM Patent Rights, and to sublicense such rights subject to certain sublicensing fees and royalty payments. In consideration for the rights granted to the Company, under the license agreement as amended in December 2016, the Company paid UM $50,000 in fees in 2016 and in January 2017 issued UM an aggregate of 33,058 shares of its common stock. In connection with the Company's commercialization or sublicensing of certain products covered by the license agreement, including CMX521, the Company could be required to pay royalties on net sales of such products ranging from 0.25% to 2% . Beginning in 2024, the Company is also subject to certain minimum annual royalty payments. The UM license agreement requires that the Company use commercially reasonable efforts to develop and make commercially available licensed products as soon as practicable. Specifically, the Company has agreed to make the first commercial sale of a licensed product by June of 2026. UM may terminate the license agreement if the Company materially breaches the license agreement. The Company is currently in compliance with its milestone requirements.

Restructuring Costs

Restructuring Costs	6 Months Ended
	Jun. 30, 2019
Restructuring and Related Activities [Abstract]
Restructuring Costs	Restructuring Costs In May 2019, the Company made the decision to discontinue the development of oral and IV BCV development programs for the treatment of Adenovirus (AdV) in pediatric stem-cell transplant (HCT) patients. The Company's development efforts with respect to BCV are now focused on the treatment of smallpox. As a result, the Company restructured its operations, which included a reduction in workforce of 43 full-time employees and the accrual of expenses to close-out the two Phase 2 clinical trials (study 210 and study 211), one Phase 3 (AdAPT) clinical trial and other supportive BCV development programs. The Company recorded charges for one-time employee termination benefits of $3.3 million , contract close-out costs of $2.8 million , and other BCV development costs of $0.3 million during the three months ended June 30, 2019 . The $2.8 million of contract close-out costs were recorded through an increase in liabilities of $2.1 million with the remainder recognized through the expensing of prepaid balances. As of June 30, 2019 , the Company had a clinical trial accrual balance related to the AdAPT, 210 and 211 trial terminations of $2.1 million , other development costs accrual of $0.3 million and a severance accrual balance of $1.8 million , which are expected to be fully paid by June 2020. The following table summarizes the restructuring charges (in thousands) recorded for the three months ended June 30, 2019 : Employee Termination Benefits Clinical Trial Close-out Costs Other Development Costs Total Research and development 1,426 2,837 315 4,578 General and administrative 1,909 — — 1.909 Total restructuring expenses 3,335 2,837 315 6,487 The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for the three months ended June 30, 2019 . No additional charges are expected to be incurred. Employee Termination Benefits Clinical Trial Close-out Costs Other Development Costs Total Balance at March 31, 2019 — — — — Accruals 3,335 2,131 315 5,781 Payments (1,551 ) (69 ) — (1,620 ) Balance at June 30, 2019 1,784 2,062 315 4,161

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events through the issuance date of these financial statements to ensure that this filing includes appropriate disclosure of events both recognized in the financial statements as of June 30, 2019 , and events which occurred subsequently but were not recognized in the financial statements. On July 26, 2019, the Company entered into an exclusive worldwide license agreement with Cantex Pharmaceuticals (Cantex) for the development and commercialization of CX-01, the lead indication for which is first line AML. In exchange for the exclusive worldwide license to CX-01, Cantex received an upfront payment of $30.0 million and 10.0 million shares of the Company's common stock. Cantex is also eligible to receive milestone payments upon completion of certain regulatory and net sales events as well as tiered royalty payments based on percentages of net sales.

The Business and Summary of S_2

The Business and Summary of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Company’s audited financial statements and notes thereto included in its Annual Report on Form 10-K for the year ended December 31, 2018 . In the opinion of the Company’s management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of its financial position, operating results and cash flows for the periods presented have been included. Operating results for the three and six months ended June 30, 2019 are not necessarily indicative of the results that may be expected for the full year, for any other interim period or for any future year.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of certain financial instruments, including accounts receivable, accounts payable and accrued expenses approximate their fair values due to the short-term nature of such instruments. For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data are based primarily upon estimates and are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, fair value measurements cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the calculated current or future fair values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The determination of where an asset or liability falls in the hierarchy requires significant judgment. These levels are: • Level 1 — Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2 — Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and models for which all significant inputs are observable, either directly or indirectly. • Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement.
Revenue Recognition	Revenue Recognition Policy The Company’s revenues generally consist of (i) contract revenue - revenue generated under federal contracts, and (ii) collaboration and licensing revenue - revenue related to non-refundable upfront fees, royalties and milestone payments earned under license agreements. Revenue is recognized in accordance with the criteria outlined in Accounting Standards Codification (ASC) 606 issued by the Financial Accounting Standards Board (FASB). Following this accounting pronouncement, a five-step approach is applied for recognizing revenue, including (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation.
Research and Development Prepaids and Accruals	Research and Development Prepaids and Accruals As part of the process of preparing financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines prepaid and accrual estimates through discussion with applicable personnel and outside service providers as to the progress or state of communication of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its prepaid and accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2019 , there had been no material adjustments to the Company’s prior period estimates of prepaid and accruals for research and development expenses. The Company’s research and development prepaids and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.
Basic and Diluted Net Loss Per Share of Common Stock	Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of non-vested restricted stock, stock options, and employee stock purchase plan purchase rights. Diluted net loss per share of common stock is computed by dividing net loss by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of warrants to purchase common stock, non-vested restricted stock, stock options, and employee stock purchase plan purchase rights outstanding during the period calculated in accordance with the treasury stock method, but are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during the periods of net loss, there was no difference between basic and diluted loss per share of common stock for the three and six months ended June 30, 2019 and 2018 .
Impact of Recently Issued Accounting Standards and Impact of Recently Adopted Accounting Standards	Impact of Recently Issued Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which amends the impairment model by requiring entities to use a forward-looking approach on expected losses to estimate credit losses on certain financial instruments, including trade receivables and available-for-sale debt securities. The new guidance will be effective for the Company beginning in the first quarter of 2020, with early adoption permitted. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements. Impact of Recently Adopted Accounting Standards In February 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-02, “Leases (Topic 842)”, which has been amended through subsequent ASUs, and which increases transparency and comparability among companies accounting for lease transactions. The most significant change of this update requires the recognition of lease assets and liabilities on the balance sheet for lessees for operating lease arrangements with lease terms greater than 12 months. This ASU is effective for financial statements issued for annual periods and interim periods within those annual periods, beginning after December 15, 2018. The Company adopted this standard effective January 1, 2019 using the alternative modified retrospective adoption method allowed by ASU 2018-11. The Company elected to use the package of three practical expedients which allows the Company not to reassess whether contracts are or contain leases, lease classification, and whether initial direct costs qualify for capitalization. The Company has completed its assessment of the impact of the standard and determined that the only material leases that the Company holds are real estate operating leases. Upon adoption of the standard, the Company recorded a right of use asset of $1.4 million and lease liability of $1.6 million on its consolidated balance sheets with no adjustment to beginning retained earnings in the period of adoption.

The Business and Summary of S_3

The Business and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Schedule of certain assets measured at fair value on a recurring basis	Below are tables that present information about certain assets measured at fair value on a recurring basis (in thousands): Fair Value Measurements June 30, 2019 Total Quoted Prices in Significant Other Significant Cash equivalents Money market funds $ 11,906 $ 11,906 $ — $ — Commercial paper 5,835 — 5,835 — Total cash equivalents 17,741 11,906 5,835 — Short-term investments U.S. treasury securities 38,405 38,405 — — Common stock of U.S. corporation 8 8 — — Commercial paper 45,673 — 45,673 — Corporate bonds 52,669 — 52,669 — Total short-term investments 136,755 38,413 98,342 — Total assets $ 154,496 $ 50,319 $ 104,177 $ — Fair Value Measurements December 31, 2018 Total Quoted Prices in Significant Other Significant Cash equivalents Money market funds $ 30,726 $ 30,726 $ — $ — U.S. treasury securities 11,482 11,482 — — Commercial paper 29,677 — 29,677 — Corporate bonds 4,008 — 4,008 — Total cash equivalents 75,893 42,208 33,685 — Short-term investments U.S. treasury securities 12,589 12,589 — — Common stock of U.S. corporation 38 38 — — Commercial paper 60,114 — 60,114 — Corporate bonds 32,683 — 32,683 — Total short-term investments 105,424 12,627 92,797 — Total assets $ 181,317 $ 54,835 $ 126,482 $ —
Schedule of accrued liabilities	Accrued liabilities consisted of the following (in thousands): June 30, 2019 December 31, 2018 Accrued research and development expenses $ 6,378 $ 4,525 Accrued compensation 4,154 2,469 Other accrued liabilities 1,422 1,281 Total accrued liabilities $ 11,954 $ 8,275

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of short-term and long-term investments	The following tables summarize the Company's debt investments (in thousands): June 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate bonds $ 52,595 $ 74 $ — $ 52,669 U.S. treasury securities 38,379 27 (1 ) 38,405 Commercial paper 45,649 25 (1 ) 45,673 Total investments $ 136,623 $ 126 $ (2 ) $ 136,747 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Corporate bonds $ 32,724 $ — $ (41 ) $ 32,683 Commercial paper 60,159 — (45 ) 60,114 U.S. treasury securities 12,592 — (3 ) 12,589 Total investments $ 105,475 $ — $ (89 ) $ 105,386
Summary of investments with unrealized losses, aggregated by investment type and the length of time	The following tables summarize the Company's debt investments with unrealized losses, aggregated by investment type and the length of time that individual investments have been in a continuous unrealized loss position (in thousands, except number of securities): June 30, 2019 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Commercial paper $ 6,955 $ (1 ) $ — $ — $ 6,955 $ (1 ) U.S. treasury securities 9,980 (1 ) — — 9,980 (1 ) Total $ 16,935 $ (2 ) $ — $ — $ 16,935 $ (2 ) Number of securities with unrealized losses 4 — 4 December 31, 2018 Less than 12 Months Greater than 12 Months Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate bonds $ 32,683 $ (41 ) $ — $ — $ 32,683 $ (41 ) Commercial paper 60,114 (45 ) — — 60,114 (45 ) U.S. treasury securities 12,589 (3 ) — — 12,589 (3 ) Total $ 105,386 $ (89 ) $ — $ — $ 105,386 $ (89 ) Number of securities with unrealized losses 36 — 36
Summary of the scheduled maturity of company investments	The following table summarizes the scheduled maturity for the Company's debt investments at June 30, 2019 (in thousands): Maturing in one year or less $ 136,747 Maturing after one year through two years — Total debt investments 136,747 Common stock of U.S. corporation 8 Total investments $ 136,755

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating Lease Right-of-Use Assets and Liabilities	The following table sets forth the operating lease right-of-use assets and liabilities as of June 30, 2019 (in thousands): Assets Operating Lease Right-of-Use Assets $ 969 Liabilities Operating Lease Short-term Liabilities (recorded within Accrued liabilities) $ 618 Operating Lease Long-term Liabilities (recorded within Lease-related obligations) 519 Total Operating Lease Liabilities $ 1,137
Operating Lease Maturity	Operating lease payments over the remainder of the lease terms are as follows (in thousands): Years Ending December 31, As of June 30, 2019 2019 $ 365 2020 719 2021 182 Total future minimum rental payments $ 1,266 Less amount of lease payments representing interest 129 Total present value of lease payments $ 1,137
Operating Lease Maturity	As of December 31, 2018 , future minimum payments under operating leases under ASC 840 were as follows (in thousands): Years Ending December 31, As of December 31, 2018 2019 $ 786 2020 797 2021 235 Total future minimum rental payments $ 1,818
Sublease Income	Total future minimum rentals under the non-cancelable operating sublease are presented below (in thousands): Years Ending December 31, As of June 30, 2019 2019 $ 39 2020 81 2021 14 Total future minimum sublease rentals $ 134

Equity Transactions and Share_2

Equity Transactions and Share-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Schedule of employee and non-employee share-based compensation expense recognized related to stock options, the ESPP and RSUs	Total share-based compensation expense recognized related to stock options, the ESPP and RSUs was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development expense $ 1,000 $ 1,536 $ 2,270 $ 2,856 General and administrative expense 1,367 2,500 4,170 4,571 Total share-based compensation expense $ 2,367 $ 4,036 $ 6,440 $ 7,427

Restructuring Costs (Tables)

Restructuring Costs (Tables)	6 Months Ended
	Jun. 30, 2019
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table summarizes the restructuring charges (in thousands) recorded for the three months ended June 30, 2019 : Employee Termination Benefits Clinical Trial Close-out Costs Other Development Costs Total Research and development 1,426 2,837 315 4,578 General and administrative 1,909 — — 1.909 Total restructuring expenses 3,335 2,837 315 6,487
Schedule of Restructuring Reserve by Type of Cost	The following table sets forth the accrual activity for employee termination benefits and contract close-out costs (in thousands) for the three months ended June 30, 2019 . No additional charges are expected to be incurred. Employee Termination Benefits Clinical Trial Close-out Costs Other Development Costs Total Balance at March 31, 2019 — — — — Accruals 3,335 2,131 315 5,781 Payments (1,551 ) (69 ) — (1,620 ) Balance at June 30, 2019 1,784 2,062 315 4,161

The Business and Summary of S_4

The Business and Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value, Separate Account Investment [Line Items]
Unrealized loss on equity investment	$ (22)	$ (78)	$ (30)	$ (212)
Short-term investments	136,755		136,755		$ 105,424
Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	17,741		17,741		75,893
Short-term investments	136,755		136,755		105,424
Total assets	154,496		154,496		181,317
Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	11,906		11,906		42,208
Short-term investments	38,413		38,413		12,627
Total assets	50,319		50,319		54,835
Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	5,835		5,835		33,685
Short-term investments	98,342		98,342		92,797
Total assets	104,177		104,177		126,482
Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0		0		0
Short-term investments	0		0		0
Total assets	0		0		0
Money market funds | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	11,906		11,906		30,726
Money market funds | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	11,906		11,906		30,726
Money market funds | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0		0		0
Money market funds | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0		0		0
U.S. treasury securities | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					11,482
Short-term investments	38,405		38,405		12,589
U.S. treasury securities | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					11,482
Short-term investments	38,405		38,405		12,589
U.S. treasury securities | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					0
Short-term investments	0		0		0
U.S. treasury securities | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					0
Short-term investments	0		0		0
Commercial paper | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	5,835		5,835		29,677
Short-term investments	45,673		45,673		60,114
Commercial paper | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0		0		0
Short-term investments	0		0		0
Commercial paper | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	5,835		5,835		29,677
Short-term investments	45,673		45,673		60,114
Commercial paper | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents	0		0		0
Short-term investments	0		0		0
Corporate bonds | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					4,008
Short-term investments	52,669		52,669		32,683
Corporate bonds | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					0
Short-term investments	0		0		0
Corporate bonds | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					4,008
Short-term investments	52,669		52,669		32,683
Corporate bonds | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Cash equivalents					0
Short-term investments	0		0		0
Common stock of U.S. corporation | Fair value, measurements, recurring
Fair Value, Separate Account Investment [Line Items]
Short-term investments	8		8		38
Common stock of U.S. corporation | Fair value, measurements, recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	8		8		38
Common stock of U.S. corporation | Fair value, measurements, recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0		0		0
Common stock of U.S. corporation | Fair value, measurements, recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Separate Account Investment [Line Items]
Short-term investments	0		0		$ 0
ContraVir investment | Common stock of U.S. corporation
Fair Value, Separate Account Investment [Line Items]
Unrealized loss on equity investment	$ 22	$ 78	$ 30	$ 212

The Business and Summary of S_5

The Business and Summary of Significant Accounting Policies - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Accrued research and development expenses	$ 6,378	$ 4,525
Accrued compensation	4,154	2,469
Other accrued liabilities	1,422	1,281
Total accrued liabilities	$ 11,954	$ 8,275

The Business and Summary of S_6

The Business and Summary of Significant Accounting Policies - Revenue Recognition (Details) $ in Thousands	3 Months Ended		6 Months Ended		101 Months Ended	112 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)	May 31, 2020USD ($)base_segmentrevenue_contractoption_segment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue	$ 1,438	$ 1,193	$ 3,794	$ 1,983
BARDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue	$ 1,400	$ 1,200	$ 3,800	$ 2,000	$ 66,300
Scenario, Forecast | BARDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue						$ 74,300
Total number of base segments | base_segment						1
Total number of option segments | option_segment						4
Total number of separate contracts | revenue_contract						5
Scenario, Forecast | BARDA Second Option Segment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue						$ 23,900
Scenario, Forecast | BARDA Third Option Segment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue						14,100
Expense reimbursement | Scenario, Forecast | BARDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue						75,800
Fees | Scenario, Forecast | BARDA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract revenue						$ 5,300

The Business and Summary of S_7

The Business and Summary of Significant Accounting Policies - Impact of Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 969
Operating lease liability	$ 1,137
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 1,400
Operating lease liability		$ 1,600

Investments - Summary of Availa

Investments - Summary of Available-for-Sale securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Amortized Cost	$ 136,623	$ 105,475
Gross Unrealized Gains	126	0
Gross Unrealized Losses	(2)	(89)
Estimated Fair Value	136,747	105,386
Corporate bonds
Schedule of Investments [Line Items]
Amortized Cost	52,595	32,724
Gross Unrealized Gains	74	0
Gross Unrealized Losses	0	(41)
Estimated Fair Value	52,669	32,683
U.S. treasury securities
Schedule of Investments [Line Items]
Amortized Cost	38,379	12,592
Gross Unrealized Gains	27	0
Gross Unrealized Losses	(1)	(3)
Estimated Fair Value	38,405	12,589
Commercial paper
Schedule of Investments [Line Items]
Amortized Cost	45,649	60,159
Gross Unrealized Gains	25	0
Gross Unrealized Losses	(1)	(45)
Estimated Fair Value	$ 45,673	$ 60,114

Investments - Summary of Invest

Investments - Summary of Investments with Unrealized Losses, Aggregated by Investment Type and the Length of Time (Details) $ in Thousands	Jun. 30, 2019USD ($)security	Dec. 31, 2018USD ($)security
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 16,935	$ 105,386
Unrealized loss, less than 12 months	(2)	(89)
Fair value, greater than 12 months	0	0
Unrealized loss, greater than 12 months	0	0
Fair value, total	16,935	105,386
Unrealized loss, total	$ (2)	$ (89)
Number of securities with unrealized losses, less than 12 months | security	4	36
Number of securities with unrealized losses, greater than 12 months | security	0	0
Number of securities with unrealized losses, total | security	4	36
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months		$ 32,683
Unrealized loss, less than 12 months		(41)
Fair value, greater than 12 months		0
Unrealized loss, greater than 12 months		0
Fair value, total		32,683
Unrealized loss, total		(41)
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	$ 6,955	60,114
Unrealized loss, less than 12 months	(1)	(45)
Fair value, greater than 12 months	0	0
Unrealized loss, greater than 12 months	0	0
Fair value, total	6,955	60,114
Unrealized loss, total	(1)	(45)
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Fair value, less than 12 months	9,980	12,589
Unrealized loss, less than 12 months	(1)	(3)
Fair value, greater than 12 months	0	0
Unrealized loss, greater than 12 months	0	0
Fair value, total	9,980	12,589
Unrealized loss, total	$ (1)	$ (3)

Investments - Schedule of Inves

Investments - Schedule of Investment Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 136,747
Maturing after one year through two years	0
Total debt investments	136,747	$ 105,386
Common stock of U.S. corporation	8
Total investments	$ 136,755

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)ft²	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)ft²	Jun. 30, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Weighted average remaining lease term	1 year 274 days		1 year 274 days
Rent expense under non-cancelable operating leases	$ 182	$ 181	$ 376	$ 351
Weighted average discount rate	13.07%		13.07%
Lease payments	$ 194	186	$ 386	370
Area of sublease space (in sq ft) | ft²	3,537		3,537
Sublease income	$ 18		$ 35
Reduction in rent expense for sublease		$ 18		$ 35

Commitments and Contingencies_2

Commitments and Contingencies - Operating Lease Right-of-Use Assets and Liabilities (Details) $ in Thousands	Jun. 30, 2019USD ($)
Assets
Operating Lease Right-of-Use Assets	$ 969
Liabilities
Operating Lease Short-term Liabilities (recorded within Accrued liabilities)	618
Operating Lease Long-term Liabilities (recorded within Lease-related obligations)	519
Total present value of lease payments	$ 1,137

Commitments and Contingencies_3

Commitments and Contingencies - Maturity Analysis of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 365
2020	719
2021	182
Total future minimum rental payments	1,266
Less amount of lease payments representing interest	129
Total present value of lease payments	$ 1,137
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019		$ 786
2020		797
2021		235
Total future minimum rental payments		$ 1,818

Commitments and Contingencies_4

Commitments and Contingencies - Minimum Sublease Rentals (Details) $ in Thousands	Jun. 30, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 39
2020	81
2021	14
Total future minimum sublease rentals	$ 134

Equity Transactions and Share_3

Equity Transactions and Share-based Compensation (Details) - USD ($) $ in Millions	Feb. 05, 2019	Jan. 01, 2019	May 31, 2019	Apr. 30, 2019	Jun. 30, 2019	Jun. 30, 2019	Feb. 28, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, restricted stock award, gross (in shares)					201,000	369,000
Accelerating vesting period	15 months		12 months
Acceleration compensation	$ 1.8		$ 0.7
The 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, evergreen option provision, equity increase						4.00%
Additional shares authorized (in shares)		2,000,000
Number of shares reserved for future issuance (in shares)					2,300,000	2,300,000
Shares issued pursuant to the exercise of stock options (in shares)					6,000	14,000
The 2013 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, evergreen option provision, equity increase						1.00%
Additional shares authorized (in shares)		422,535
Number of shares reserved for future issuance (in shares)					2,400,000	2,400,000
Number of shares authorized to be granted (in shares)					3,100,000	3,100,000	704,225
Number of shares reserved for issuance, annual increase (in shares)						422,535
Percentage of pay that employee can contribute, maximum					15.00%	15.00%
Discounted purchase price from market price, offering date						15.00%
Discounted purchase price from market price, purchase date						15.00%
Shares issued pursuant to employee stock purchase plan (in shares)					0	113,000
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)				1,750,000
Chief Executive Officer | Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Expiration period				10 years
Year One | Chief Executive Officer | Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Year Two | Chief Executive Officer | Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Year Three | Chief Executive Officer | Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Year Four | Chief Executive Officer | Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%

Equity Transactions and Share_4

Equity Transactions and Share-based Compensation - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 2,367	$ 4,036	$ 6,440	$ 7,427
Research and development expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	1,000	1,536	2,270	2,856
General and administrative expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 1,367	$ 2,500	$ 4,170	$ 4,571

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2019
Income Tax Contingency [Line Items]
Federal or state income taxes	$ 0
Unrecognized tax benefits	$ 0
Scenario, Forecast
Income Tax Contingency [Line Items]
Estimated annual effective tax rate		0.00%

Significant Agreements (Details

Significant Agreements (Details) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended	101 Months Ended	112 Months Ended
	Jan. 31, 2017shares	Feb. 28, 2011extension	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2016USD ($)	Jun. 30, 2019USD ($)	May 31, 2020USD ($)	Dec. 31, 2018USD ($)
Long-term Purchase Commitment [Line Items]
Contract revenue			$ 1,438	$ 1,193	$ 3,794	$ 1,983
Fair value of investment			8		8			$ 8
ContraVir investment | Common Stock
Long-term Purchase Commitment [Line Items]
Fair value of investment			8		8			8		$ 38
BARDA
Long-term Purchase Commitment [Line Items]
Number of extension periods | extension		4
Contract revenue			$ 1,400	$ 1,200	$ 3,800	$ 2,000		$ 66,300
BARDA | Scenario, Forecast
Long-term Purchase Commitment [Line Items]
Contract revenue									$ 74,300
BARDA | Expense reimbursement | Scenario, Forecast
Long-term Purchase Commitment [Line Items]
Contract revenue									75,800
BARDA | Fees | Scenario, Forecast
Long-term Purchase Commitment [Line Items]
Contract revenue									5,300
BARDA Second Option Segment | Scenario, Forecast
Long-term Purchase Commitment [Line Items]
Contract revenue									23,900
BARDA Third Option Segment | Scenario, Forecast
Long-term Purchase Commitment [Line Items]
Contract revenue									$ 14,100
The Regents of the University of Michigan
Long-term Purchase Commitment [Line Items]
Shares issued (in shares) | shares	33,058
The Regents of the University of Michigan | Minimum
Long-term Purchase Commitment [Line Items]
Royalties percentage							0.25%
The Regents of the University of Michigan | Maximum
Long-term Purchase Commitment [Line Items]
Royalties percentage							2.00%
Licensing Agreement | The Regents of the University of Michigan
Long-term Purchase Commitment [Line Items]
Fees paid							$ 50

Restructuring Costs (Details)

Restructuring Costs (Details) $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2019employee	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)
Restructuring Cost and Reserve [Line Items]
Reduction in workforce | employee	43
One-time employee termination benefits		$ 3,335
Accrued contract close-out costs		2,837
Other BCV development costs		315
Accruals		5,781
Accrual balance		4,161	$ 0
Trial Terminations
Restructuring Cost and Reserve [Line Items]
Accruals		2,131
Accrual balance		2,062	0
Other Development Costs
Restructuring Cost and Reserve [Line Items]
Accruals		315
Accrual balance		315	0
Severance Accrual Balance
Restructuring Cost and Reserve [Line Items]
Accruals		3,335
Accrual balance		$ 1,784	$ 0

Restructuring Costs - Summary o

Restructuring Costs - Summary of Restructuring Charges (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2019USD ($)
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits	$ 3,335
Clinical Trial Close-out Costs	2,837
Other Development Costs	315
Total	6,487
Research and development expense
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits	1,426
Clinical Trial Close-out Costs	2,837
Other Development Costs	315
Total	4,578
General and administrative expense
Restructuring Cost and Reserve [Line Items]
Employee Termination Benefits	1,909
Clinical Trial Close-out Costs	0
Other Development Costs	0
Total	$ 1,909

Restructuring Costs - Accrual A

Restructuring Costs - Accrual Activity for Restructuring Accrual (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2019USD ($)
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	$ 0
Accruals	5,781
Payments	(1,620)
Balance at June 30, 2019	4,161
Employee Termination Benefits
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	0
Accruals	3,335
Payments	(1,551)
Balance at June 30, 2019	1,784
Clinical Trial Close-out Costs
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	0
Accruals	2,131
Payments	(69)
Balance at June 30, 2019	2,062
Other Development Costs
Restructuring Reserve [Roll Forward]
Balance at March 31, 2019	0
Accruals	315
Payments	0
Balance at June 30, 2019	$ 315

Subsequent Events (Details)

Subsequent Events (Details) - Cantex - Subsequent Event shares in Millions, $ in Millions	Jul. 26, 2019USD ($)shares
Subsequent Event [Line Items]
Shares issued (in shares) | shares	10
Licensing Agreement
Subsequent Event [Line Items]
Fees paid | $	$ 30