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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2018	May 14, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Trading Symbol	ALT
Entity Registrant Name	ALTIMMUNE, INC.
Entity Central Index Key	0001326190
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		25,802,072

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 4,559,894	$ 8,769,465
Restricted cash	3,534,174	3,534,174
Total cash, cash equivalents, and restricted cash	8,094,068	12,303,639
Accounts receivable	3,754,976	3,806,239
Tax refunds receivable	6,622,352	6,361,657
Prepaid expenses and other current assets	1,449,364	994,332
Total current assets	19,920,760	23,465,867
Property and equipment, net	1,374,927	603,146
Intangible assets, net	39,345,901	38,722,270
Other assets	225,133	238,917
Total assets	60,866,721	63,030,200
Current liabilities:
Notes payable	49,702	49,702
Accounts payable	513,168	129,075
Accrued expenses	4,528,125	3,625,257
Current portion of deferred revenue	44,753	19,753
Current portion of deferred rent	19,385	15,914
Total current liabilities	5,155,133	3,839,701
Deferred income taxes	5,440,450	5,938,402
Other long-term liabilities	3,776,390	4,574,507
Total liabilities	14,371,973	14,352,610
Contingencies (Note 14)
Stockholders' equity:
Common stock, $0.0001 par value; 100,000,000 shares authorized; 22,271,635 and 18,127,119 shares issued; 22,250,337 and 18,103,691 shares outstanding at March 31, 2018 and December 31, 2017, respectively	2,225	1,810
Additional paid-in capital	125,357,899	121,655,838
Accumulated deficit	(80,858,377)	(77,684,839)
Accumulated other comprehensive loss - foreign currency translation adjustments	(3,961,515)	(4,576,986)
Total stockholders' equity	40,540,232	39,395,823
Total liabilities and stockholders' equity	60,866,721	63,030,200
Series B Redeemable Convertible Preferred Stock [Member]
Current liabilities:
Series B redeemable convertible preferred stock; $0.0001 par value; 16,000 shares designated; 6,958 and 12,177 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively; aggregate liquidation and redemption value of $5,954,516 at March 31, 2018	$ 5,954,516	$ 9,281,767

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	22,271,635	18,127,119
Common stock, shares outstanding	22,250,337	18,103,691
Series B Redeemable Convertible Preferred Stock [Member]
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares designated	16,000	16,000
Convertible preferred stock, shares issued	6,958	12,177
Convertible preferred stock, shares outstanding	6,958	12,177
Convertible preferred stock, aggregate liquidation	$ 5,954,516
Convertible preferred stock, redemption value	$ 5,954,516

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue
Research grants and contracts	$ 2,686,042	$ 294,633
License revenue	4,938	4,938
Total revenue	2,690,980	299,571
Operating expenses
Research and development	5,746,971	2,786,122
General and administrative	2,447,894	2,030,516
Goodwill impairment charges	490,676
Total operating expenses	8,685,541	4,816,638
Loss from operations	(5,994,561)	(4,517,067)
Other income (expense)
Changes in fair value of warrant liability	1,547,982
Changes in fair value of embedded derivative	(7,042)
Interest expense	(870)	(60,603)
Interest income	31,590
Other income (expense), net	257,725	(1,111)
Total other income (expense), net	1,829,385	(61,714)
Net loss before income tax benefit	(4,165,176)	(4,578,781)
Income tax benefit	991,638
Net loss	(3,173,538)	(4,578,781)
Other comprehensive income - foreign currency translation adjustments	615,471	579,836
Comprehensive loss	(2,558,067)	(3,998,945)
Net loss	(3,173,538)	(4,578,781)
Preferred stock accretion and dividends	(1,891,321)	(118,356)
Net loss attributable to common stockholders	$ (5,064,859)	$ (4,697,137)
Weighted-average common shares outstanding, basic and diluted	20,145,270	6,917,708
Net loss per share attributable to common stockholders, basic and diluted	$ (0.25)	$ (0.68)

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($)	Total	Series B Redeemable Convertible Preferred Stock [Member]	Common Stock [Member] Series B Preferred Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2016		$ 5,993
Beginning Balance (in shares) at Dec. 31, 2016		599,285
Ending Balance at Mar. 31, 2017		$ 5,993
Ending Balance (in shares) at Mar. 31, 2017		599,285
Beginning Balance at Dec. 31, 2016	$ 32,207,323		$ 692	$ 71,034,899	$ (31,259,449)	$ (7,574,812)
Beginning Balance (in shares) at Dec. 31, 2016			6,917,204
Stock based compensation	197,135			197,135
Vesting of restricted stock	147,967			147,967
Vesting of restricted stock (in shares)			4,970
Exercises of stock options	450			450
Exercises of stock options (in shares)			596
Warrant issuance, net of deferred financing costs	548,956			548,956
Foreign currency translation adjustments	579,836					579,836
Net loss	(4,578,781)				(4,578,781)
Ending Balance at Mar. 31, 2017	29,102,886		$ 692	71,929,407	(35,838,230)	(6,994,976)
Ending Balance (in shares) at Mar. 31, 2017			6,922,770
Beginning Balance at Dec. 31, 2017		$ 9,281,767
Beginning Balance (in shares) at Dec. 31, 2017		12,177
Conversion of Series B redeemable convertible preferred stock into common stock		$ (5,218,572)
Conversion of Series B redeemable convertible preferred stock into common stock (in shares)		(5,219)
Accretion of Series B redeemable convertible preferred stock		$ 1,891,321
Ending Balance at Mar. 31, 2018		$ 5,954,516
Ending Balance (in shares) at Mar. 31, 2018		6,958
Beginning Balance at Dec. 31, 2017	39,395,823		$ 1,810	121,655,838	(77,684,839)	(4,576,986)
Beginning Balance (in shares) at Dec. 31, 2017			18,103,691
Stock based compensation	363,788			363,788
Vesting of restricted stock	(7,049)		$ 1	(7,050)
Vesting of restricted stock (in shares)			2,130
Exercises of stock options	$ 18,488		$ 23	18,465
Exercises of stock options (in shares)	775,391		231,098
Conversion of Series B convertible preferred stock into common stock	$ 5,218,570		$ 391	5,218,179
Conversion of Series B convertible preferred stock into common stock (in shares)			3,913,418
Accretion of Series B redeemable convertible preferred stock	(1,891,321)			(1,891,321)
Foreign currency translation adjustments	615,471					615,471
Net loss	(3,173,538)				(3,173,538)
Ending Balance at Mar. 31, 2018	$ 40,540,232		$ 2,225	$ 125,357,899	$ (80,858,377)	$ (3,961,515)
Ending Balance (in shares) at Mar. 31, 2018			22,250,337

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (3,173,538)	$ (4,578,781)
Adjustments to reconcile net loss to net cash used in operating activities:
Goodwill impairment charges	490,676
Stock-based compensation	356,709	345,036
Depreciation	25,062	12,966
Amortization	14,628	12,555
Debt discount and deferred financing charge accretion		38,270
Changes in fair value of warrant liability	(1,547,982)
Changes in fair value of embedded derivative	7,042
Changes in operating assets and liabilities:
Accounts receivable	51,263	129,664
Prepaid expenses and other current assets	246,403	50,553
Accounts payable	376,347	1,566,604
Accrued expenses	716,934	(733,736)
Deferred revenue	20,062	20,062
Deferred rent	49,845	(3,362)
Tax refunds receivable	(694,200)	(203,008)
Deferred tax liabilities	(497,952)
Net cash used in operating activities	(3,558,701)	(3,343,177)
CASH FLOWS FROM INVESTING ACTIVITIES:
Refund of cash held in escrow		200,000
Purchase of property and equipment	(652,635)	(39,582)
Additions to intangible assets	(14,828)	(17,295)
Net cash (used in) provided by investing activities	(667,463)	143,123
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of convertible notes, net of issuance costs		3,018,780
Proceeds from exercise of stock options	18,488	450
Proceeds from stock subscriptions		35,020
Net cash provided by financing activities	18,488	3,054,250
EFFECT OF EXCHANGE RATES ON CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(1,895)	7,399
Net decrease in cash, cash equivalents, and restricted cash	(4,209,571)	(138,405)
Cash, cash equivalents, and restricted cash - beginning of period	12,303,639	2,876,113
Cash, cash equivalents, and restricted cash - end of period	8,094,068	2,737,708
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest	870	7,181
SUPPLEMENTAL NON-CASHFINANCING ACTIVITIES:
Addition of property and equipment not yet paid	142,950
Addition of intangible assets not yet paid	12,273
Lease incentive billed but not yet received	684,972
Accrued expense capitalized as convertible notes		842,604
Common stock warrants issued in connection with convertible notes		$ 566,793
Series B Redeemable Convertible Preferred Stock [Member]
SUPPLEMENTAL NON-CASHFINANCING ACTIVITIES:
Conversion of preferred stock into common stock	5,218,570
Accretion of Series B redeemable convertible preferred stock	$ 1,891,321

Nature of Business and Basis of Presentation	3 Months Ended
Nature of Business and Basis of Presentation	Mar. 31, 2018
Accounting Policies [Abstract]
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Altimmune, Inc., headquartered in Gaithersburg, Maryland, together with its subsidiaries (collectively, the “Company” or “Altimmune”) is a clinical stage biopharmaceutical company incorporated under the laws of the State of Delaware. The Company is focused on discovering and developing immunotherapies and vaccines to address significant unmet medical needs. Since its inception, the Company has devoted substantially all of its efforts to business planning, research and development, recruiting management and technical staff, and raising capital, and has financed its operations through the issuance of common and preferred stock, long-term debt, and proceeds from research grants and government contracts. The Company has not generated any revenues from the sale of any products to date, and there is no assurance of any future revenues from product sales. The Company’s business is a result of a merger between PharmAthene, Inc. (“PharmAthene”) and the business previously known as Altimmune, Inc. (“Private Altimmune”). In May of 2017, Private Altimmune merged with PharmAthene pursuant to an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) dated January 18, 2017 among Private Altimmune, PharmAthene, its wholly owned acquisition subsidiaries Mustang Merger Sub Corp I Inc. (“Merger Sub Corp”) and Mustang Merger Sub II LLC (“Merger Sub LLC”). Pursuant to the Merger Agreement, Merger Sub LLC agreed to acquire 100% of the outstanding capital stock of Private Altimmune in a reverse triangular merger and reorganization pursuant to section 368(a) of the Internal Revenue Code (the “Mergers”) (see Note 4). Prior to the Mergers, PharmAthene was a publicly traded biodefense company engaged in Phase 2 clinical trials in developing a next generation anthrax vaccine. On May 4, 2017, Private Altimmune and PharmAthene closed the Mergers in accordance with the terms of the Merger Agreement. Upon the closing of the Mergers, (i) Merger Sub Corp merged with and into Private Altimmune, with Private Altimmune remaining as the surviving corporation; (ii) Private Altimmune then merged with and into Merger Sub LLC, with Merger Sub LLC (renamed as “Altimmune LLC”) remaining as the surviving entity; and (iii) PharmAthene was renamed as “Altimmune, Inc.” Upon closing of the Mergers, all equity instruments of Private Altimmune were exchanged for corresponding equity instruments of PharmAthene (see Note 4). Except where the context indicates otherwise, references to “we,” “us,” “our,” “Altimmune” or the “Company” refer, for periods prior to the completion of the Mergers, to Private Altimmune and its subsidiaries, and for periods following the completion of the Mergers, to the combined company and its subsidiaries. The accompanying unaudited condensed consolidated financial statements are prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, they do not include all of the information and disclosures required by accounting principles generally accepted in the United States for complete consolidated financial statements and should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2017 included in the annual report on Form 10-K which was filed with the SEC on April 2, 2018. In the opinion of management, we have prepared the accompanying unaudited condensed consolidated financial statements on the same basis as our audited consolidated financial statements, and these condensed consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the results of the interim periods presented. The operating results for the interim periods presented are not necessarily indicative of the results expected for the full year 2018 or any future years or periods. The unaudited condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded assets and liabilities that might be necessary should we be unable to continue as a going concern.

Going Concern	3 Months Ended
Going Concern	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Going Concern	2. Going Concern The accompanying unaudited condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern. The Company has experienced recurring losses in past years. The Company incurred a net loss of $3,173,538 and used $3,558,701 in cash to fund operations during the three months ended March 31, 2018, and had an accumulated deficit of $80,858,377 as of March 31, 2018. The Company expects to incur additional losses in the future in connection with research and development and other activities. Since inception, the Company has financed its activities principally from the issuance of equity and debt securities. The Company’s ability to continue as a going concern is dependent upon the Company’s ability to raise additional debt and equity capital. There can be no assurance that such capital will be available in sufficient amounts or on terms acceptable to the Company. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The accompanying unaudited condensed consolidated financial statements do not include any adjustments relating to the recoverability of the recorded assets or the classification of liabilities that may be necessary should the Company be unable to continue as a going concern. As of March 31, 2018, the Company does not have sufficient capital to fund its plan of operations for a twelve-month period from the expected issuance date of its financial statements as of and for the three months ended March 31, 2018. In order to address its capital needs, including its planned clinical trials, the Company must continue to actively pursue additional equity or debt financing. The Company has been in ongoing discussions with institutional investors and investment banks with respect to such financing. Adequate financing opportunities might not be available to the Company, when and if needed, on acceptable terms, or at all. If the Company is unable to obtain additional financing in sufficient amounts or on acceptable terms under such circumstances the Company’s operating results and prospects will be adversely affected.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies Segment information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, our Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. We view our operations and manage our business in one operating segment, the research and development of immunotherapies and vaccines. Recently Issued Accounting Pronouncements In February 2016, FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 requires a lessee to separate the lease components from the non-lease components in a contract and recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. It also aligns lease accounting for lessors with the revenue recognition guidance in ASU 2014-09. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied at the beginning of the earliest period presented using a modified retrospective approach. We expect the adoption of ASU 2016-02 will not have a material impact on our financial statements.

Business Combination

3 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

Business Combination

4. Business Combination

Pursuant to the Merger Agreement, the Company closed the Mergers with PharmAthene on May 4, 2017. In accordance with the terms of the Merger Agreement, PharmAthene issued 0.749106 (the “share exchange ratio”) of a share of PharmAthene common stock for each share of Private Altimmune’s common stock (“common stock”) outstanding as of the closing date. In addition, Private Altimmune’s stock options and warrants were also replaced with options and warrants, to purchase PharmAthene’s common stock at the same share exchange ratio of 0.749106. All historical share and per share information including common and preferred stock, restricted stock, common stock warrants, and stock options, has been retroactively adjusted to reflect the effect of the share exchange ratio. Immediately prior to closing, 599,285 shares of Series B convertible preferred stock (“convertible preferred stock”) converted into Private Altimmune common stock on a 1-for-1 basis. In addition, outstanding principal and accrued interest on the convertible notes that were issued in January 2017 (the “Notes”) converted into 316,734 shares of Private Altimmune common stock. Further, 39,758 shares of Private Altimmune common stock were issued pursuant to the accelerated vesting of restricted stock, and 660,715 shares of Private Altimmune common stock were issued as a result of warrant exercises, both in accordance with their original terms. Upon the closing of the Mergers, Private Altimmune common stock totaling 6,883,498 shares were exchanged for 6,883,498 shares of PharmAthene common stock.

Although PharmAthene was the issuer of the shares and considered the legal acquirer in the Mergers, following the closing, shareholders of Private Altimmune held 58.2% of the equity interest of the combined entity and assumed control of the combined entity. As a result, the transaction has been accounted for as a reverse merger, with Private Altimmune considered the accounting acquirer, and the assets and liabilities of PharmAthene have been recorded at their estimated fair value. The unadjusted purchase price allocated to PharmAthene’s assets and liabilities was estimated to be $44,742,737 as of the closing date and consisted of the shares of the combined company retained by PharmAthene shareholders, and the estimated fair value of vested PharmAthene stock options and warrants which remained outstanding as of the closing date. Also at the closing, 7,569 outstanding unvested options of PharmAthene with an estimated fair value of $15,173 remained subject to vesting and service requirements. These unvested options will be recorded as operating expense in future periods as the services are delivered and the options vest.

Headquartered in Annapolis, Maryland, PharmAthene was incorporated in Delaware in April 2005. PharmAthene was a biodefense company engaged in Phase 2 clinical trials in developing a next generation anthrax vaccine. The next generation vaccine is intended to have more rapid time to protection, fewer doses for protection and less stringent requirements for temperature-controlled storage and handling than the currently used vaccine. The Mergers enable the combined company to become a fully integrated, commercially-focused immunotherapeutics company with the ability to create more value than either company could achieve individually. As a publicly listed entity, the Mergers also provide us with additional capital financing alternatives to support the combined entity’s planned research and development activities.

In addition to the operating assets and liabilities of PharmAthene, Private Altimmune also acquired PharmAthene’s tax attributes, which primarily consisted of tax refunds receivable and $965,583 of net operating losses which were limited under Section 382 of the U.S. Internal Revenue Service and were fully reserved, which will expire in 2023. The Company recorded a deferred tax liability related to future tax benefits arising from an in-process research and development asset (“IPR&D”) acquired in the Mergers. Goodwill generated from the Mergers is not expected to be deductible for tax purposes.

For accounting purposes, the historical financial statements of Private Altimmune have not been adjusted to reflect the Mergers, other than adjustments to the capital structure of Private Altimmune to reflect the historical capital structure of PharmAthene. Private Altimmune incurred $2,183,671 of transaction costs, which were expensed as incurred.

The following table lists the various securities of PharmAthene which were outstanding as of May 4, 2017 and whose rights and obligations were assumed by the combined entity following the Mergers:


Outstanding PharmAthene common stock		6,883,498
Outstanding PharmAthene stock options		123,003
Outstanding PharmAthene stock warrants		4,658
Per share fair value of PharmAthene common stock	$	6.50
Weighted average per share fair value of PharmAthene stock options, vested and unvested	$	0.26
Per share fair value of PharmAthene stock warrants	$	0.01
Aggregate fair value of consideration	$	44,757,910
Less fair value of unvested common stock options		(15,173	)

Total fair value of consideration	$	44,742,737

Through December 31, 2017, the Company had recorded adjustments to the allocation of the purchase consideration that included a $44,700 adjustment to increase our tax refund receivable and a $4,535 adjustment to reduce our deferred tax liabilities, with a total adjustment of $49,235 resulting in an increase in goodwill. The adjustments were the result of a change in the tax rate being applied from 34% to 35%. Those purchase price adjustments were reflected in the consolidated balance sheet as of December 31, 2017.

During the three months ended March 31, 2018, the Company recorded adjustments to the purchase price allocation resulting in a net decrease in tax refunds receivable, with a corresponding net increase in goodwill, of $490,676. The initial tax receivable was recorded based on an estimate of taxable loss for PharmAthene’s operations from January 1, 2017 to May 4, 2017 prior to the Mergers. During the preparation of its tax return, management revised its taxable loss calculations for warrant expenses and state tax refunds, resulting in the decrease to tax refunds receivable.

The adjusted allocation of the purchase consideration was as follows:


Cash and cash equivalents	$	13,684,535
Accounts receivable		1,124,462
Prepaid expenses and other current assets		597,172
Tax refunds receivable		1,556,558
Property and equipment		75,779
IPR&D		22,389,000
Goodwill		16,064,498

Total assets acquired		55,492,004

Accounts payable and accrued expenses		(2,193,785	)
Deferred tax liability		(8,555,482	)

Total liabilities assumed		(10,749,267	)

Net assets acquired	$	44,742,737

The Company relied on significant Level 3 unobservable inputs to estimate the fair value of acquired IPR&D assets using management’s estimate of future revenue and expected profitability of the products after taking into account an estimate of future expenses, net of contract revenue and other funding, necessary to bring the products to completion. These projected cash flows were then discounted to their present values using a discount rate of 23%, which was considered commensurate with the risks and stages of development of the products.

From the date of the Mergers through December 31, 2017, the Company experienced a significant decline in the trading price of our common stock which indicated potential impairment. Based on the results of our impairment tests performed during 2017, we had concluded that our goodwill was impaired and its full carrying value, including goodwill generated from the Mergers, was written off as an impairment charge during the year ended December 31, 2017. During the three months ended March 31, 2018, the Company recorded an additional goodwill impairment charge of $490,676 as a result of the purchase price allocation adjustments recorded during the period. There was no goodwill balance outstanding at March 31, 2018.

The operating activities of PharmAthene have been included in the accompanying condensed consolidated financial statements from the date of the Mergers. For the three months ended March 31, 2018, revenues and net income of PharmAthene included in the accompanying condensed consolidated financial statements aggregated $770,981 and $20,269, respectively.

The following unaudited pro forma information for the three months ended March 31, 2017 gives effect to the acquisition of PharmAthene as if the Mergers had occurred on January 1, 2017:


Pro forma revenue	$	1,103,642
Pro forma net loss attributable to common stockholders	$	(5,832,724	)
Pro forma weighted-average common shares outstanding, basic and diluted		15,084,150
Pro forma net loss per share attributable to common stockholders, basic and diluted	$	(0.39	)

Significant nonrecurring pro forma adjustments included (i) the reversal of acquisition costs of $823,143; (ii) PharmAthene stock compensation expenses of $66,180 for the three months ended March 31, 2017 that would have been incurred prior to the pro forma acquisition date had the Mergers occurred on January 1, 2017; and (iii) accelerated vesting of restricted stock upon the Mergers of $91,957.

Net Loss Per Share

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Net Loss Per Share

5. Net Loss Per Share

Because we have reported a net loss attributable to common stockholders for all periods presented, basic and diluted net loss per share attributable to common stockholders are the same for all periods presented. All historical share and per share information including common and preferred stock, restricted stock, common stock warrants, and stock options, has been retroactively adjusted to reflect the effect of the share exchange ratio (Note 4).

The following table sets forth the computation of basic and diluted net loss per share:


	Three Months Ended March 31,
	2018			2017
Numerator:
Net loss	$	(3,173,538	)	$	(4,578,781	)
Less: preferred stock accretion and dividends		(1,891,321	)		(118,356	)

Net loss attributable to common stockholders	$	(5,064,859	)	$	(4,697,137	)

Denominator:
Weighted-average common share outstanding, basic and diluted		20,145,270			6,917,708

Net loss per share attributable to common stockholders, basic and diluted	$	(0.25	)	$	(0.68	)

Potential common shares issuable upon conversion, vesting or exercise of convertible preferred stock, Series B redeemable preferred stock (“redeemable preferred stock”), unvested restricted stock, common stock warrants, and stock options that are excluded from the computation of diluted weighted-average shares outstanding are as follows:


	Three Months Ended March 31,
	2018		2017
Redeemable preferred stock		2,606,028		—
Convertible preferred stock		—		599,285
Unvested restricted stock		21,298		69,576
Common stock warrants		2,350,085		661,888
Common stock options		1,706,243		1,205,324

Intangible Assets

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

6. Intangible Assets

Our intangible assets consisted of the following:


	March 31, 2018
	Estimated Useful Lives		Gross Carrying Value		Accumulated Amortization			Net Book Value
Internally developed patents		6-10 years	$	705,441	$	(259,845	)	$	445,596
Acquired licenses		16-20 years		285,000		(241,724	)		43,276

Total intangible assets subject to amortization				990.441		(501,569	)		488,872
IPR&D assets		Indefinite		38,857,029		—			38,857,029

Total			$	39,847,470	$	(501,569	)	$	39,345,901


	December 31, 2017
	Estimated Useful Lives		Gross Carrying Value		Accumulated Amortization			Net Book Value
Internally developed patents		6-10 years	$	678,340	$	(249,601	)	$	428,739
Acquired licenses		16-20 years		285,000		(237,340	)		47,660

Total intangible assets subject to amortization				963,340		(486,941	)		476,399
IPR&D assets		Indefinite		38,245,871		—			38,245,871

Total			$	39,209,211	$	(486,941	)	$	38,722,270

Changes in the carrying amounts of IPR&D assets for the three months ended March 31, 2018 were:


Balance, beginning of period	$	38,245,871
Foreign currency translation adjustments		611,158

Balance, end of period	$	38,857,029

Amortization expense of intangible assets subject to amortization totaled $14,628 and $12,555 for the three months ended March 31, 2018 and 2017, respectively. Amortization expense was classified as research and development expenses in the accompanying condensed consolidated statements of operations and comprehensive loss.

As of March 31, 2018, future estimated amortization expense is as follows:


Years ending December 31,
Remainder of 2018	$	40,319
2019		50,003
2020		36,556
2021		15,997
2022		15,997
2023 and thereafter		330,000

Total	$	488,872

Accrued Expenses

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Accrued Expenses

7. Accrued Expenses

Accrued expenses consist of the following:


	March 31, 2018		December 31, 2017
Accrued professional services	$	486,556	$	835,326
Accrued payroll and employee benefits		614,628		909,455
Accrued interest		536		536
Accrued construction costs		67,620		328,384
Accrued property and equipment purchases		142,950		—
Accrued research and development costs		3,215,835		1,551,556

Total	$	4,528,125	$	3,625,257

Other Long-Term Liabilities

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Other Long-Term Liabilities

8. Other Long-Term Liabilities

Other long-term liabilities consist of the following:


	March 31, 2018		December 31, 2017
Unvested restricted stock	$	286	$	315
BPI France notes		616,371		599,927
Deferred revenue, long-term portion		154,733		159,671
Deferred rent, long-term portion		1,117,835		386,489
Common stock warrant liability		1,852,887		3,400,869
Embedded derivative		34,278		27,236

Total	$	3,776,390	$	4,574,507

Beneficial Conversion Feature

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Beneficial Conversion Feature

9. Beneficial Conversion Feature

A summary of the periodic changes in beneficial conversion feature embedded in the redeemable preferred stock as of March 31, 2018 is as follows:


Balance, beginning of period	$	1,338,840
Amount released during the period		(502,065	)

Balance, end of period	$	836,775

Embedded Derivative

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Embedded Derivative

10. Embedded Derivative

A summary of the periodic changes in the fair value of the derivative financial instrument embedded in the redeemable preferred stock as of March 31, 2018 is as follows:


Balance, beginning of period	$	27,236
Changes in fair value		7,042

Balance, end of period	$	34,278

The fair value used to determine the initial carrying value of the derivative financial instrument embedded in the redeemable preferred stock was measured using Level 3 inputs and was estimated using the Monte Carlo simulation valuation model. The assumptions used to estimate the fair value of the embedded redemption derivative financial instrument were as follows:


	March 31, 2018			December 31, 2017
Expected volatility		56.60	%		59.60	%
Incremental borrowing rate		12.00	%		12.00	%
Risk-free interest rate		1.84	%		1.59	%

Warrants

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Warrants

11. Warrants

A summary of warrant activity during the three months ended March 31, 2018 and 2017 is as follows:


	Three Months Ended March 31,
	2018		2017
Warrants outstanding, beginning of period		2,350,085		612,112
Issuances		—		49,776

Warrants outstanding, end of period		2,350,085		661,888

For warrants classified as a liability, the following is a summary of the periodic changes in their fair value at March 31, 2018:


Balance, beginning of period	$	3,400,869
Changes in fair value		(1,547,982	)

Balance, end of period	$	1,852,887

The fair value of common warrants classified as a liability was estimated using the Monte Carlo simulation valuation model with Level 3 inputs. The following assumptions were used to estimate the fair value of warrants that were classified as a liability at March 31, 2018 and December 31, 2017:


	March 31, 2018			December 31, 2017
Expected volatility		86.70	%		91.30	%
Expected term (years)		4.35			4.60
Risk-free interest rate		2.51	%		2.16	%
Expected dividend yield		0.00	%		0.00	%

For warrants classified as permanent equity, the fair value used to determine their initial carrying value was measured using Level 3 inputs and was estimated using the Black-Scholes option pricing model. The following assumptions were used to estimate the fair value of warrants issued during the three months ended March 31, 2017:


Expected volatility	84.40	%
Expected term (years)	5.00
Risk-free interest rate	2.13	%
Expected dividend yield	0.00	%

Stock-Based Compensation

3 Months Ended

Mar. 31, 2018

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

Stock-Based Compensation

12. Stock-Based Compensation

Stock Options

Our stock option awards generally vest over four years and have a contractual life of ten years. During the three months ended March 31, 2018, we granted 134,500 stock options with a weighted-average exercise price of $1.82 per share and per share weighted-average grant date fair value of $1.37. At March 31, 2018, there was $1,780,743 of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 2.19 years.

Information related to stock options at March 31, 2018 is as follows:


	Number of Stock Options		Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding		1,706,243	$	4.55		4.37	$	138,896

Exercisable		775,391	$	5.19		4.05	$	138,896

Expected to vest		930,852	$	4.02		4.65	$	—

Restricted Stock

At March 31, 2018, we had 21,298 shares of unvested restricted stock with total unrecognized compensation expense of $10,811, which we expect to recognize over a weighted-average period of 2.50 years. During the three months ended March 31, 2018 and 2017, we released 2,130 and 4,970 shares of common stock from restriction, respectively, as a result of the vesting of restricted stock.

Stock-based compensation expense

Stock-based compensation expense is classified in the accompanying condensed consolidated statements of operations and comprehensive loss as follows:


	Three Months Ended March 31,
	2018		2017
Research and development	$	89,036	$	75,075
General and administrative		267,673		269,961

Total	$	356,709	$	345,036

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company recorded an income tax benefit of $991,638 for the three months ended March 31, 2018. Income taxes for the three months ended March 31, 2018 included discrete tax benefits of $18,351 related to excess tax benefits associated with share-based compensation, and $271,356 related to a change in estimate. Excluding discrete items, the Company’s effective tax rate was 16.9% which represents a $479,601 benefit due to the Company’s projected 2018 unlimited lived Federal net operating loss that we have determined to be realizable and a $222,330 tax benefit due to the ability to carry back Maryland state NOLs generated in 2018. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Act (“SAB 118”) which allows the Company to record provisional amounts during a measurement period not to extend beyond one year from the enactment date. Since the Tax Cuts and Jobs Act (“TCJA”) was passed in December 2017, additional regulatory guidance and accounting interpretation are expected to be released over the next year, and significant data and analysis will be required to finalize amounts recorded pursuant to TCJA. The Company considers the accounting for the deferred tax re-measurements and other items to be incomplete due to the forthcoming guidance and its ongoing analysis of final year-end data and tax positions. The Company expects to complete its analysis within the measurement period in accordance with SAB 118. The Company did not change any provisional estimates recognized in 2017 which would impact the statement of operations. Any adjustments to these amounts will be recorded to current tax expense in 2018 when the analysis is complete.

Contingencies	3 Months Ended
Contingencies	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies	14. Contingencies We are a party in various contractual disputes, litigation, and potential claims arising in the ordinary course of business. We do not believe that the resolution of these matters will have a material adverse effect on our financial position or results of operations.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Segment information	Segment information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, our Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. We view our operations and manage our business in one operating segment, the research and development of immunotherapies and vaccines.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 requires a lessee to separate the lease components from the non-lease components in a contract and recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. It also aligns lease accounting for lessors with the revenue recognition guidance in ASU 2014-09. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and is to be applied at the beginning of the earliest period presented using a modified retrospective approach. We expect the adoption of ASU 2016-02 will not have a material impact on our financial statements.

Business Combination (Tables)

3 Months Ended

Mar. 31, 2018

Business Combinations [Abstract]

Schedule of Lists of Various Securities

The following table lists the various securities of PharmAthene which were outstanding as of May 4, 2017 and whose rights and obligations were assumed by the combined entity following the Mergers:


Outstanding PharmAthene common stock		6,883,498
Outstanding PharmAthene stock options		123,003
Outstanding PharmAthene stock warrants		4,658
Per share fair value of PharmAthene common stock	$	6.50
Weighted average per share fair value of PharmAthene stock options, vested and unvested	$	0.26
Per share fair value of PharmAthene stock warrants	$	0.01
Aggregate fair value of consideration	$	44,757,910
Less fair value of unvested common stock options		(15,173	)

Total fair value of consideration	$	44,742,737

Schedule of Purchase Price Allocation

The adjusted allocation of the purchase consideration was as follows:


Cash and cash equivalents	$	13,684,535
Accounts receivable		1,124,462
Prepaid expenses and other current assets		597,172
Tax refunds receivable		1,556,558
Property and equipment		75,779
IPR&D		22,389,000
Goodwill		16,064,498

Total assets acquired		55,492,004

Accounts payable and accrued expenses		(2,193,785	)
Deferred tax liability		(8,555,482	)

Total liabilities assumed		(10,749,267	)

Net assets acquired	$	44,742,737

Summary of Unaudited Pro Forma Information

The following unaudited pro forma information for the three months ended March 31, 2017 gives effect to the acquisition of PharmAthene as if the Mergers had occurred on January 1, 2017:


Pro forma revenue	$	1,103,642
Pro forma net loss attributable to common stockholders	$	(5,832,724	)
Pro forma weighted-average common shares outstanding, basic and diluted		15,084,150
Pro forma net loss per share attributable to common stockholders, basic and diluted	$	(0.39	)

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share

The following table sets forth the computation of basic and diluted net loss per share:


	Three Months Ended March 31,
	2018			2017
Numerator:
Net loss	$	(3,173,538	)	$	(4,578,781	)
Less: preferred stock accretion and dividends		(1,891,321	)		(118,356	)

Net loss attributable to common stockholders	$	(5,064,859	)	$	(4,697,137	)

Denominator:
Weighted-average common share outstanding, basic and diluted		20,145,270			6,917,708

Net loss per share attributable to common stockholders, basic and diluted	$	(0.25	)	$	(0.68	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	Three Months Ended March 31,
	2018		2017
Redeemable preferred stock		2,606,028		—
Convertible preferred stock		—		599,285
Unvested restricted stock		21,298		69,576
Common stock warrants		2,350,085		661,888
Common stock options		1,706,243		1,205,324

Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

Our intangible assets consisted of the following:


	March 31, 2018
	Estimated Useful Lives		Gross Carrying Value		Accumulated Amortization			Net Book Value
Internally developed patents		6-10 years	$	705,441	$	(259,845	)	$	445,596
Acquired licenses		16-20 years		285,000		(241,724	)		43,276

Total intangible assets subject to amortization				990.441		(501,569	)		488,872
IPR&D assets		Indefinite		38,857,029		—			38,857,029

Total			$	39,847,470	$	(501,569	)	$	39,345,901


	December 31, 2017
	Estimated Useful Lives		Gross Carrying Value		Accumulated Amortization			Net Book Value
Internally developed patents		6-10 years	$	678,340	$	(249,601	)	$	428,739
Acquired licenses		16-20 years		285,000		(237,340	)		47,660

Total intangible assets subject to amortization				963,340		(486,941	)		476,399
IPR&D assets		Indefinite		38,245,871		—			38,245,871

Total			$	39,209,211	$	(486,941	)	$	38,722,270

Schedule of Changes in Carrying Amounts of IPR&D Assets

Changes in the carrying amounts of IPR&D assets for the three months ended March 31, 2018 were:


Balance, beginning of period	$	38,245,871
Foreign currency translation adjustments		611,158

Balance, end of period	$	38,857,029

Schedule of Future Estimated Amortization Expense

As of March 31, 2018, future estimated amortization expense is as follows:


Years ending December 31,
Remainder of 2018	$	40,319
2019		50,003
2020		36,556
2021		15,997
2022		15,997
2023 and thereafter		330,000

Total	$	488,872

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following:


	March 31, 2018		December 31, 2017
Accrued professional services	$	486,556	$	835,326
Accrued payroll and employee benefits		614,628		909,455
Accrued interest		536		536
Accrued construction costs		67,620		328,384
Accrued property and equipment purchases		142,950		—
Accrued research and development costs		3,215,835		1,551,556

Total	$	4,528,125	$	3,625,257

Other Long-Term Liabilities (Tables)

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Summary of Other Long-Term Liabilities

Other long-term liabilities consist of the following:


	March 31, 2018		December 31, 2017
Unvested restricted stock	$	286	$	315
BPI France notes		616,371		599,927
Deferred revenue, long-term portion		154,733		159,671
Deferred rent, long-term portion		1,117,835		386,489
Common stock warrant liability		1,852,887		3,400,869
Embedded derivative		34,278		27,236

Total	$	3,776,390	$	4,574,507

Beneficial Conversion Feature (Tables)

3 Months Ended

Mar. 31, 2018

Text Block [Abstract]

Summary of Periodic Changes in Beneficial Conversion Feature Embedded in the Redeemable Preferred Stock

A summary of the periodic changes in beneficial conversion feature embedded in the redeemable preferred stock as of March 31, 2018 is as follows:


Balance, beginning of period	$	1,338,840
Amount released during the period		(502,065	)

Balance, end of period	$	836,775

Embedded Derivative (Tables)

3 Months Ended

Mar. 31, 2018

Summary of Periodic Changes in Fair Value of Derivative Financial Instrument Embedded

A summary of the periodic changes in the fair value of the derivative financial instrument embedded in the redeemable preferred stock as of March 31, 2018 is as follows:


Balance, beginning of period	$	27,236
Changes in fair value		7,042

Balance, end of period	$	34,278

Assumptions Used to Estimate Fair Value of Embedded Redemption Derivative Financial Instrument


	March 31, 2018			December 31, 2017
Expected volatility		56.60	%		59.60	%
Incremental borrowing rate		12.00	%		12.00	%
Risk-free interest rate		1.84	%		1.59	%

Monte Carlo Simulation Model [Member]

Assumptions Used to Estimate Fair Value of Embedded Redemption Derivative Financial Instrument


	March 31, 2018			December 31, 2017
Expected volatility		86.70	%		91.30	%
Expected term (years)		4.35			4.60
Risk-free interest rate		2.51	%		2.16	%
Expected dividend yield		0.00	%		0.00	%

Black Scholes Option Pricing Model [Member]

Assumptions Used to Estimate Fair Value of Embedded Redemption Derivative Financial Instrument


Expected volatility	84.40	%
Expected term (years)	5.00
Risk-free interest rate	2.13	%
Expected dividend yield	0.00	%

Warrants (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Summary of Warrant Activity

A summary of warrant activity during the three months ended March 31, 2018 and 2017 is as follows:


	Three Months Ended March 31,
	2018		2017
Warrants outstanding, beginning of period		2,350,085		612,112
Issuances		—		49,776

Warrants outstanding, end of period		2,350,085		661,888

Summary of Periodic Changes in Fair Value of Warrant Liability

For warrants classified as a liability, the following is a summary of the periodic changes in their fair value at March 31, 2018:


Balance, beginning of period	$	3,400,869
Changes in fair value		(1,547,982	)

Balance, end of period	$	1,852,887

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

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

Schedule of Information Related to Stock Options Outstanding

Information related to stock options at March 31, 2018 is as follows:


	Number of Stock Options		Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding		1,706,243	$	4.55		4.37	$	138,896

Exercisable		775,391	$	5.19		4.05	$	138,896

Expected to vest		930,852	$	4.02		4.65	$	—

Schedule of Stock-based Compensation Expense

Stock-based compensation expense is classified in the accompanying condensed consolidated statements of operations and comprehensive loss as follows:


	Three Months Ended March 31,
	2018		2017
Research and development	$	89,036	$	75,075
General and administrative		267,673		269,961

Total	$	356,709	$	345,036

Nature of Business and Basis of Presentation - Additional Information (Detail) - Merger Agreement [Member]	3 Months Ended
	Mar. 31, 2018
Business And Basis Of Presentation [Line Items]
Agreement of reorganization and merger date	Jan. 18, 2017
Merger Sub Corp I Inc and Mustang Merger Sub II LLC [Member]
Business And Basis Of Presentation [Line Items]
Business acquisition, percentage of voting interest acquired	100.00%

Going Concern - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ (3,173,538)	$ (4,578,781)
Cash used to fund operations	(3,558,701)	$ (3,343,177)
Accumulated deficit	$ (80,858,377)		$ (77,684,839)

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018 Segment
Accounting Policies [Abstract]
Number of operating segments	1

Business Combination - Additional Information (Detail)		3 Months Ended		12 Months Ended
Business Combination - Additional Information (Detail)	May 04, 2017 USD ($) shares	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Share exchange ratio		1-for-1 basis
Debt converted in to equity	316,734
Conversion of stock \| shares	6,883,498
Transaction costs	$ 2,183,671
Increase in goodwill from recorded adjustments		$ 490,676
Discount rate	23.00%
Goodwill		0
Goodwill impairment charge		490,676
Revenue		2,690,980	$ 299,571
Net Income		(3,173,538)	$ (4,578,781)
Accelerated vesting of restricted stock		91,957
Restricted Stock Units (RSUs) [Member]
Business Acquisition [Line Items]
Conversion of stock \| shares	39,758
Series B Preferred Stock [Member]
Business Acquisition [Line Items]
Conversion of preferred stock	$ 599,285
Common Stock Class A [Member]
Business Acquisition [Line Items]
Common stock issued \| shares	6,883,498
United States [Member]
Business Acquisition [Line Items]
Operating loss carryforwards		$ 965,583
Operating loss carryforwards, expiration date		Jan. 01, 2023
Reversal of Acquisition Related Costs [Member]
Business Acquisition [Line Items]
Nonrecurring pro forma adjustments		$ 823,143
Common Stock Warrants [Member]
Business Acquisition [Line Items]
Conversion of stock \| shares	660,715
PharmAthene [Member]
Business Acquisition [Line Items]
Reverse stock split of common stock	0.749106
Equity interests acquired	58.20%
Total fair value of consideration	$ 44,742,737
Outstanding unvested options \| shares	7,569
Stock options estimated fair value	$ 15,173
Increase tax refund receivable due to adjustments to the allocation of the purchase consideration				$ 44,700
Reduce deferred tax liability due to adjustments to the allocation of the purchase consideration				4,535
Increase in goodwill due to adjustments to the allocation of the purchase consideration				$ 49,235
Change in tax rate		35.00%		34.00%
Goodwill	$ 16,064,498
Revenue		$ 770,981
Net Income		20,269
Nonrecurring pro forma adjustments		(5,832,724)
PharmAthene [Member] \| Stock Compensation Expense [Member]
Business Acquisition [Line Items]
Nonrecurring pro forma adjustments		$ 66,180

Business Combination - Schedule of Lists of Various Securities (Detail) - USD ($)	May 04, 2017	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Outstanding PharmAthene common stock		22,250,337	18,103,691
Outstanding PharmAthene stock options			1,706,243
Weighted average per share fair value of PharmAthene stock options, vested and unvested			$ 4.55
PharmAthene [Member]
Business Acquisition [Line Items]
Outstanding PharmAthene common stock	6,883,498
Outstanding PharmAthene stock options	123,003
Outstanding PharmAthene stock warrants	4,658
Per share fair value of PharmAthene common stock	$ 6.50
Weighted average per share fair value of PharmAthene stock options, vested and unvested	0.26
Per share fair value of PharmAthene stock warrants	$ 0.01
Aggregate fair value of consideration	$ 44,757,910
Less fair value of unvested common stock options	(15,173)
Total fair value of consideration	$ 44,742,737

Business Combination - Schedule of Purchase Price Allocation (Detail) - USD ($)	Mar. 31, 2018	May 04, 2017
Business Acquisition [Line Items]
Goodwill	$ 0
PharmAthene [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		$ 13,684,535
Accounts receivable		1,124,462
Prepaid expenses and other current assets		597,172
Tax refunds receivable		1,556,558
Property and equipment		75,779
IPR&D		22,389,000
Goodwill		16,064,498
Total assets acquired		55,492,004
Accounts payable and accrued expenses		(2,193,785)
Deferred tax liability		(8,555,482)
Total liabilities assumed		(10,749,267)
Net assets acquired		$ 44,742,737

Business Combination - Summary of Unaudited Pro Forma Information (Detail) - PharmAthene [Member]	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Business Acquisition [Line Items]
Pro forma revenue	$ 1,103,642
Pro forma net loss attributable to common stockholders	$ (5,832,724)
Pro forma weighted-average common shares outstanding, basic and diluted \| shares	15,084,150
Pro forma net loss per share attributable to common stockholders, basic and diluted \| $ / shares	$ (0.39)

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net loss	$ (3,173,538)	$ (4,578,781)
Less: preferred stock accretion and dividends	(1,891,321)	(118,356)
Net loss attributable to common stockholders	$ (5,064,859)	$ (4,697,137)
Denominator:
Weighted-average common share outstanding, basic and diluted	20,145,270	6,917,708
Net loss per share attributable to common stockholders, basic and diluted	$ (0.25)	$ (0.68)

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		599,285
Series B Redeemable Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,606,028
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,706,243	1,205,324
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,350,085	661,888
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	21,298	69,576

Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Intangible Assets [Line Items]
Total intangible assets, Gross Carrying Value	$ 39,847,470	$ 39,209,211
Intangible assets subject to amortization, Gross Carrying Value	990,441	963,340
Intangible assets subject to amortization, Accumulated Amortization	(501,569)	(486,941)
Intangible assets subject to amortization, Net Book Value	488,872	476,399
Total intangible assets, Net Book Value	39,345,901	38,722,270
IPR&D [Member]
Schedule Of Intangible Assets [Line Items]
Intangible assets, Net Book Value	38,857,029	38,245,871
Internally Developed Patents [Member]
Schedule Of Intangible Assets [Line Items]
Intangible assets subject to amortization, Gross Carrying Value	705,441	678,340
Intangible assets subject to amortization, Accumulated Amortization	(259,845)	(249,601)
Intangible assets subject to amortization, Net Book Value	$ 445,596	$ 428,739
Internally Developed Patents [Member] \| Minimum [Member]
Schedule Of Intangible Assets [Line Items]
Estimated Useful Lives	6 years	6 years
Internally Developed Patents [Member] \| Maximum [Member]
Schedule Of Intangible Assets [Line Items]
Estimated Useful Lives	10 years	10 years
Acquired Licenses [Member]
Schedule Of Intangible Assets [Line Items]
Intangible assets subject to amortization, Gross Carrying Value	$ 285,000	$ 285,000
Intangible assets subject to amortization, Accumulated Amortization	(241,724)	(237,340)
Intangible assets subject to amortization, Net Book Value	$ 43,276	$ 47,660
Acquired Licenses [Member] \| Minimum [Member]
Schedule Of Intangible Assets [Line Items]
Estimated Useful Lives	16 years	16 years
Acquired Licenses [Member] \| Maximum [Member]
Schedule Of Intangible Assets [Line Items]
Estimated Useful Lives	20 years	20 years

Intangible Assets - Schedule of Changes in Carrying Amounts of IPR&D Assets (Detail) - IPR&D [Member]	3 Months Ended
	Mar. 31, 2018 USD ($)
Indefinite-lived Intangible Assets [Line Items]
IPR&D Balance, beginning of period	$ 38,245,871
IPR&D, Foreign currency translation adjustments	611,158
IPR&D Balance, end of period	$ 38,857,029

Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 14,628	$ 12,555

Intangible Assets - Schedule of Future Estimated Amortization Expense (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2018	$ 40,319
2019	50,003
2020	36,556
2021	15,997
2022	15,997
2023 and thereafter	330,000
Intangible assets subject to amortization, Net Book Value	$ 488,872	$ 476,399

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Accrued Liabilities and Other Liabilities [Abstract]
Accrued professional services	$ 486,556	$ 835,326
Accrued payroll and employee benefits	614,628	909,455
Accrued interest	536	536
Accrued construction costs	67,620	328,384
Accrued property and equipment purchases	142,950
Accrued research and development costs	3,215,835	1,551,556
Total	$ 4,528,125	$ 3,625,257

Other Long-Term Liabilities - Summary of Other Long-Term Liabilities (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unvested restricted stock	$ 286	$ 315
Deferred revenue, long-term portion	154,733	159,671
Deferred rent, long-term portion	1,117,835	386,489
Common stock warrant liability	1,852,887	3,400,869
Embedded derivative	34,278	27,236
Total	3,776,390	4,574,507
BPI France Notes [Member]
Debt Instrument [Line Items]
BPI France notes	$ 616,371	$ 599,927

- Definition

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References + Details

Beneficial Conversion Feature - Summary of Periodic Changes in Beneficial Conversion Feature Embedded in the Redeemable Preferred Stock (Detail) - Series B Redeemable Convertible Preferred Stock [Member]	3 Months Ended
	May 31, 2018 USD ($)
Conversion of Stock [Line Items]
Balance, beginning of period	$ 1,338,840
Amount released during the period	(502,065)
Balance, end of period	$ 836,775

Embedded Derivative - Summary of Periodic Changes in Fair Value of Derivative Financial Instrument Embedded (Detail)	3 Months Ended
	Mar. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Balance, beginning of period	$ 27,236
Changes in fair value	7,042
Balance, end of period	$ 34,278

Embedded Derivative - Assumptions Used to Estimate Fair Value of Embedded Redemption Derivative Financial Instrument (Detail) - Level 3 [Member]	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected volatility	56.60%	59.60%
Incremental borrowing rate	12.00%	12.00%
Risk-free interest rate	1.84%	1.59%

Warrants - Summary of Warrant Activity (Detail) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Warrants and Rights Note Disclosure [Abstract]
Warrants outstanding, beginning of period	2,350,085	612,112
Issuances		49,776
Warrants outstanding, end of period	2,350,085	661,888

Warrants - Summary of Periodic Changes in Fair Value of Warrant Liability (Detail)	3 Months Ended
	Mar. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Changes in fair value	$ (1,547,982)
Level 3 [Member] \| Common Stock Warrants [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Balance, beginning of period	3,400,869
Changes in fair value	(1,547,982)
Balance, end of period	$ 1,852,887

Warrants - Summary of Fair Value of Stock Options Issued to Employees (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	86.70%	91.30%
Expected term (years)	4 years 4 months 6 days	4 years 7 months 6 days
Risk-free interest rate	2.51%	2.16%
Expected dividend yield	0.00%	0.00%

Warrants - Summary of Assumptions Used to Estimate Fair Value of Warrants (Detail) - Common Stock Warrants [Member]	3 Months Ended
	Mar. 31, 2018
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected volatility	84.40%
Expected term (years)	5 years
Risk-free interest rate	2.13%
Expected dividend yield	0.00%

Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option vesting Period	4 years
Stock option expiration Period	10 years
Number of Stock Options, Granted	134,500
Stock options granted, weighted-average exercise price	$ 1.82
Weighted-average grant date fair value of stock options granted	$ 1.37
Unrecognized compensation cost, stock options	$ 1,780,743
Unrecognized stock-based compensation expense, period for recognition	2 years 2 months 8 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense, period for recognition	2 years 6 months
Unrecognized compensation expense	$ 10,811
Unvested restricted stock, shares	21,298
Common stock issued as result of vesting of restricted stock	2,130	4,970

Stock-Based Compensation - Schedule of Information Related to Stock Options Outstanding (Detail)	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Stock Options, Outstanding \| shares	1,706,243
Number of Stock Options, Exercised \| shares	775,391
Number of Stock Options, Expected to vest \| shares	930,852
Weighted-average Exercise Price, Outstanding \| $ / shares	$ 4.55
Weighted-average Exercise Price, Exercised \| $ / shares	5.19
Weighted-average Exercise Price, Expected to vest \| $ / shares	$ 4.02
Weighted-average Remaining Contractual Term, Outstanding	4 years 4 months 13 days
Weighted-average Remaining Contractual Term, Exercisable	4 years 18 days
Weighted-average Remaining Contractual Term, Expected to vest	4 years 7 months 24 days
Weighted-average Intrinsic Value, Outstanding \| $	$ 138,896
Weighted-average Intrinsic Value, Exercisable \| $	138,896
Weighted-average Intrinsic Value, Expected to vest \| $	$ 0

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 356,709	$ 345,036
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	89,036	75,075
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 267,673	$ 269,961

Income Taxes - Additional Information (Detail)	3 Months Ended
Income Taxes - Additional Information (Detail)	Mar. 31, 2018 USD ($)
Income Taxes [Line Items]
Income tax benefit	$ (991,638)
Excess tax benefits associated with share-based compensation	18,351
Change in estimate	$ 271,356
Effective tax rate	16.90%
United States Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforward	$ 479,601
State [Member] \| Maryland [Member]
Income Taxes [Line Items]
Net operating loss carryforward	$ 222,330