Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Mar. 14, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	VirnetX Holding Corp
Entity Central Index Key	0001082324
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 235,390,533
Entity Common Stock, Shares Outstanding		60,821,163
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,135	$ 6,627
Investments available for sale	1,453	9,249
Prepaid expenses and other current assets	591	588
Total current assets	5,179	16,464
Prepaid expenses, non-current	1,989	2,374
Property and equipment, net	7	33
Total assets	7,175	18,871
Current liabilities:
Accounts payable and accrued liabilities	414	1,806
Accrued payroll and related expenses	2,175	1,522
Income tax liability	393	396
Deferred revenue, current portion	1,500	1,500
Total current liabilities	4,482	5,224
Deferred revenue, non-current portion	1,000	2,500
Other liabilities	140	0
Commitments and contingencies (Note 4)
Total liabilities	5,622	7,724
Stockholders' equity:
Preferred stock, par value $0.0001 per share Authorized: 10,000,000 shares at December 31, 2017 and December 31, 2016, Issued and outstanding: 0 shares at December 31, 2017 and December 31, 2016	0	0
Common stock, par value $0.0001 per share Authorized: 100,000,000 shares at December 31, 2017 and December 31, 2016, Issued and outstanding: 59,051,978 shares and 58,144,888 shares, at December 31, 2017 and December 31, 2016, respectively	6	6
Additional paid-in capital	177,076	169,391
Accumulated deficit	(175,516)	(158,238)
Accumulated other comprehensive loss	(13)	(12)
Total stockholders' equity	1,553	11,147
Total liabilities and stockholders' equity	$ 7,175	$ 18,871

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
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)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	59,051,978	58,144,888
Common stock, shares outstanding (in shares)	59,051,978	58,144,888

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Revenue	$ 1,547	$ 1,550	$ 1,555
Operating expense:
Royalty expense	0	884	5,265
Research and development	2,674	2,499	2,277
Selling, general and administrative expenses	16,194	26,672	23,190
Total operating expense	18,868	30,055	30,732
Loss from operations	(17,321)	(28,505)	(29,177)
Loss on change in value of derivative liability	0	0	(117)
Interest and other income, net	46	69	68
Loss before taxes	(17,275)	(28,436)	(29,226)
Income tax expense	(3)	(133)	(8)
Net loss	$ (17,278)	$ (28,569)	$ (29,234)
Basic and diluted loss per share (in dollars per share)	$ (0.30)	$ (0.51)	$ (0.56)
Weighted average shares outstanding basic and diluted (in shares)	58,354,397	55,984,825	52,384,494

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (17,278)	$ (28,569)	$ (29,234)
Other comprehensive gain (loss), net of tax:
Change in equity adjustment from foreign currency translation, net of tax	0	3	(1)
Change in unrealized gain (loss) on investments, net of tax	(1)	4	(3)
Total other comprehensive income (loss), net of tax	(1)	7	(4)
Comprehensive loss	$ (17,279)	$ (28,562)	$ (29,238)

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Dec. 31, 2014	$ 5	$ 133,072	$ (100,435)	$ (15)	$ 32,627
Balance (in shares) at Dec. 31, 2014	51,996,701
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash exercise of warrants, net		431			431
Stock issued for cash exercise of warrants, net (in shares)	120,161
Stock issued for cash, net		3,276			3,276
Stock issued for cash, net (in shares)	835,056
Advisor warrant issuance		121			121
Stock-based compensation		7,275			7,275
Exercise of options		165			165
Exercise of options (in shares)	143,100
Stock issued for vested RSUs (in shares)	103,817
Derivative liability		438			438
Comprehensive income:
Net loss			(29,234)		(29,234)
Other comprehensive income (loss), net of tax				(4)	(4)
Comprehensive loss					(29,238)
Balance at Dec. 31, 2015	$ 5	144,778	(129,669)	(19)	15,095
Balance (in shares) at Dec. 31, 2015	53,198,835
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash, net	$ 1	19,195			19,196
Stock issued for cash, net (in shares)	4,760,594
Stock-based compensation		5,398			5,398
Exercise of options		20			20
Exercise of options (in shares)	50,357
Stock issued for vested RSUs (in shares)	135,102
Comprehensive income:
Net loss			(28,569)		(28,569)
Other comprehensive income (loss), net of tax				7	7
Comprehensive loss					(28,562)
Balance at Dec. 31, 2016	$ 6	169,391	(158,238)	(12)	11,147
Balance (in shares) at Dec. 31, 2016	58,144,888
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash, net		3,677			3,677
Stock issued for cash, net (in shares)	730,444
Stock-based compensation		3,986			3,986
Exercise of options		22			22
Exercise of options (in shares)	12,500
Stock issued for vested RSUs (in shares)	164,146
Comprehensive income:
Net loss			(17,278)		(17,278)
Other comprehensive income (loss), net of tax				(1)	(1)
Comprehensive loss					(17,279)
Balance at Dec. 31, 2017	$ 6	$ 177,076	$ (175,516)	$ (13)	$ 1,553
Balance (in shares) at Dec. 31, 2017	59,051,978

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (17,278)	$ (28,569)	$ (29,234)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	26	28	26
Amortization of warrant issuance costs	0	30	91
Stock-based compensation	3,986	5,398	7,275
Change in value of derivative liability	0	0	117
Changes in assets and liabilities:
Prepaid expenses and other current assets	(3)	66	(2)
Prepaid expense - Non-current	385	385	385
Accounts payable	(1,392)	(477)	(1,044)
Other liabilities	140	0	0
Accrued payroll and related expenses	695	232	1,207
Royalty payable	0	0	(6,100)
Related-party payable	0	(11)	(70)
Income tax liability	(3)	(4)	(8)
Deferred revenue	(1,500)	1,000	1,000
Net cash used in operating activities	(14,944)	(21,922)	(26,357)
Cash flows from investing activities:
Purchase of property and equipment	0	(13)	(10)
Purchase of investments	(946)	(10,527)	(10,673)
Proceeds from sale or maturity of investments	8,741	11,240	23,287
Net cash provided by investing activities	7,795	700	12,604
Cash flows from financing activities:
Proceeds from exercise of options	22	20	165
Proceeds from exercise of warrants	0	0	431
Proceeds from sale of common stock	3,677	19,196	3,276
Payments of taxes on cashless exercise of restricted stock units	(42)	(93)	(51)
Net cash provided by financing activities	3,657	19,123	3,821
Net decrease in cash and cash equivalents	(3,492)	(2,099)	(9,932)
Cash and cash equivalents, beginning of period	6,627	8,726	18,658
Cash and cash equivalents, end of period	3,135	6,627	8,726
Cash paid for income taxes	5	126	6
Non-cash transactions
Fair value of warrants issued for services	$ 0	$ 0	$ 121

Formation and Business of the Company	12 Months Ended
Formation and Business of the Company	Dec. 31, 2017
Formation and Business of the Company [Abstract]
Formation and Business of the Company	Note 1 − Formation and Business of the Company VirnetX Holding Corporation, which we refer to as” we”, “us”, “our”, “the Company” or “VirnetX”, is engaged in the business of commercializing a portfolio of patents. We seek to license our technology, including GABRIEL Connection Technology™, to various original equipment manufacturers, or OEMs, that use our technologies in the development and manufacturing of their own products within the IP-telephony, mobility, fixed-mobile convergence and unified communications markets. Prior to 2012 our revenue was limited to an insignificant amount of software royalties pursuant to the terms of a single license agreement. During 2013 and 2012 we had revenues from settlements of patent infringement disputes whereby we received consideration for past sales of licensees that utilized our technology, where there was no prior patent license agreement (see “Revenue Recognition”). Our portfolio of intellectual property is the foundation of our business model. We currently own approximately 185 total patents and pending applications, including 70 US patents/patent applications and 115 foreign patents/validations/pending applications. Our patent portfolio is primarily focused on securing real-time communications over the Internet, as well as related services such as the establishment and maintenance of a secure domain name registry. Our patented methods also have additional applications in the key areas of device operating systems and network security for Cloud services, M2M communications in areas of Smart City, Connected Car and Connected Home. The subject matter of all our U.S and foreign patents and pending applications relates generally to securing communications over the internet and such covers all our technology and other products. Our issued U.S. and foreign patents expire at various times during the period from 2019 to 2024. Some of our issued patents and pending patent applications were acquired by our principal operating subsidiary; VirnetX, Inc., from Leidos, (f/k/a Science Applications International Corporation or SAIC) in 2006 and we are required to make payments to Leidos, based on cash or certain other values generated from those patents. The amount of such payments depends upon the type of value generated, and certain categories are subject to maximums and other limitations.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2 − Summary of Significant Accounting Policies

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported period. The critical accounting policies we employ in the preparation of our consolidated financial statements are those which involve impairment of long-lived assets, income taxes, fair value of financial instruments and stock-based compensation.

Use of Estimates

We prepare our consolidated financial statements in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”). In doing so, we have to make estimates and assumptions that affect our reported amounts of assets, liabilities, revenues, and expenses, as well as related disclosure of contingent assets and liabilities. In some cases, we could reasonably have used different accounting policies and estimates. In some cases, changes in the accounting estimates are reasonably likely to occur from period to period. Accordingly, actual results could differ materially from our estimates. To the extent that there are material differences between these estimates and actual results, our financial condition or results of operations will be affected. We base our estimates on past experience and other assumptions that we believe are reasonable under the circumstances, and we evaluate these estimates on an ongoing basis. We refer to accounting estimates of this type as critical accounting policies and estimates, which we discuss further below. We have reviewed our critical accounting policies and estimates with the audit committee of our board of directors.

Basis of Consolidation

The consolidated financial statements include the accounts of VirnetX Holding Corporation and our wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated.

Revenue Recognition (see Note 2 -New Accounting Pronouncements - ASU No. 2014-09, Revenue from Contracts with Customers)

We derive our revenue from patent licensing. The timing and amount of revenue recognized from each licensee depends upon a variety of factors, including the specific terms of each agreement and the nature of the deliverables and obligations. Such agreements may be complex and include multiple elements. These agreements may include, without limitation, elements related to the settlement of past patent infringement liabilities, up-front and non-refundable license fees for the use of patents, patent licensing royalties on covered products sold by licensees, and the compensation structure and ownership of intellectual property rights associated with contractual technology development arrangements. Licensing agreements are accounted for under the Financial Accounting Standards Board (“FASB”) revenue recognition guidance, “Revenue Arrangements with Multiple Deliverables.” This guidance requires consideration to be allocated to each element of an agreement that has stand-alone value using the relative fair value method. In other circumstances, such as those agreements involving consideration for past and expected future patent royalty obligations, after consideration of the particular facts and circumstances, the appropriate recording of revenue between periods may require the use of judgment. In all cases, revenue is only recognized after all the following criteria are met: (1) written agreements have been executed; (2) delivery of technology or intellectual property rights has occurred or services have been rendered; (3) fees are fixed or determinable; and (4) collectability of fees is reasonably assured.

Patent License Agreements: Upon signing a patent license agreement, including licenses entered upon settlement of litigation, we provide the licensee permission to use our patented technology in specific applications. We account for patent license agreements in accordance with the guidance for revenue recognition for arrangements with multiple deliverables, with amounts allocated to each element based on their fair values. We have elected to utilize the leased-based model for revenue recognition with revenue being recognized over the expected period of benefit to the licensee. Under our patent license agreements, we do or expect to typically receive one or a combination of the following forms of payment as consideration for permitting our licensees to use our patented inventions in specific applications and products:

•

Consideration for Past Sales: Consideration related to a licensee’s product sales from prior periods may result from a negotiated agreement with a licensee that utilized our patented technology prior to signing a patent license agreement with us or from the resolution of a litigation, disagreement or arbitration with a licensee over the specific terms of an existing license agreement. We may also receive royalty for past sales in connection with the settlement of patent litigation where there was no prior patent license agreement. These amounts are negotiated, typically based upon application of a royalty rate to historical sales prior to the execution of the license agreement. In each of these cases, because delivery has occurred, we record the consideration as revenue when we have obtained a signed agreement, identified a fixed or determinable price, and determined that collectability is reasonably assured.

•

Current Royalty Payments: Ongoing royalty payments cover a licensee’s obligations to us related to its sales of covered products in the current contractual reporting period. Licensees that owe these current royalty payments are obligated to provide us with quarterly or semi-annual royalty reports that summarize their sales of covered products and their related royalty obligations to us. We expect to receive these royalty reports subsequent to the period in which our licensees’ underlying sales occurred. As a result, it is impractical for us to recognize revenue in the period in which the underlying sales occur, and, in most cases, we will recognize revenue in the period in which the royalty report is received and other revenue recognition criteria are met due to the fact that without royalty reports from our licensees, our visibility into our licensees’ sales is limited.

•

Non-Refundable Up-Front Fees and Minimum Fee Contracts: For licenses that provide for non-refundable up-front or fixed minimum fees over their term, for which we have no future obligations or performance requirements, revenue is generally recognized over the license term. For licenses that provide for fees that are not fixed or determinable, including licenses that provide for extended payment terms and/or payment of a significant portion of the fee after expiration of the license or more than 12 months after delivery, the fees are generally presumed not to be fixed or determinable, and revenue is deferred and recognized as earned, but generally not in advance of collection.

•

Non-Royalty Elements: Elements that are not related to royalty revenue in nature, such as settlement fees, expense reimbursement, and damages, if any, are recorded as gain from settlement which is reflected as a separate line item within the operating expenses section in the consolidated statements of operations.

Deferred Revenue

In August 2013, we began receiving annual payments on a contract that required payment to us over 4 years totaling $10,000 (“August 2013 Contract Settlement”). As of December 31, 2017, we received cash totaling $10,000, all of which is non-refundable. We recognized $1,500, $1,500 and $1,500 of revenue related to the August 2013 Contract Settlement during the years ended December 31, 2017, 2016 and 2015, respectively.

Activity under the August 2013 Contract Settlement was as follows:

	2017		2016		2015
Deferred Revenue, beginning of year	$	4,000	$	3,000	$	2,000
Payment received		—		2,500		2,500
Less: Amount amortized as revenue		1,500		1,500		1,500
Deferred Revenue, end of year	$	2,500	$	4,000	$	3,000

Royalty Expense

Royalty expense for the years ended December 31, 2017, 2016 and 2015 was $0, $884 and $5,265, respectively and was a result of our royalty agreement with Leidos. The agreement provides for revenue sharing and legal reimbursements related to attorney time and expenses incurred by Leidos during discovery and other aspects of litigation matters that have been resolved.

Cash and Cash Equivalents

We consider all highly liquid investments purchased with original maturities of three months or less at the date of purchase to be cash equivalents. Our cash and cash equivalents are not subject to significant interest rate risk due to the short maturities of these investments.

Prepaid Expenses and Other Current Assets

Prepaid Expense and Other Current Assets at December 31, 2017 includes the current portion of prepaid rent for a facility lease for corporate promotional and marketing purposes. Beginning March 2014, the prepayment totaling $4,000 is being amortized over the 10-year term of the lease. The unamortized non-current portion of the prepayment is included in Prepaid Expenses-Non-current on the consolidated balance sheet.

Investments

Investments are classified as available-for-sale and are recorded at fair market value. Unrealized gains and losses are reported as other comprehensive income. Realized gains and losses are recorded in income in the period they are realized. Unrealized gains and losses on our investments are included in other comprehensive income. We invest our excess cash primarily in highly liquid debt instruments including corporate, government and federal agency securities, with contractual maturities less than two years. By policy, we limit the amount of credit exposure to any one issuer.

Property and Equipment

Property and equipment are stated at historical cost, less accumulated depreciation and amortization. Depreciation and amortization are computed using the accelerated and straight-line methods over the estimated useful lives of the assets, which range from five to seven years. Repair and maintenance costs are charged to expense as incurred.

Concentration of Credit Risk and Other Risks and Uncertainties

Our cash and cash equivalents are primarily maintained at two major financial institutions in the United States. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits. A portion of those balances are insured by the Federal Deposit Insurance Corporation, or FDIC. During the year ended December 31, 2017 and 2016, we had, at times, funds that were uninsured. We do not believe that we are subject to any unusual financial risk beyond the normal risk associated with commercial banking relationships. We have not experienced any losses on our deposits of cash and cash equivalents.

Fair Value

The carrying amounts of our financial instruments, including cash equivalents, accounts payable, and accrued liabilities, approximate fair value because of their generally short maturities.

Intangible Assets

We record intangible assets at cost, less accumulated amortization. Amortization of intangible assets is provided over their estimated useful lives, which can range from 3 to 15 years, on either a straight-line basis or as revenue is generated by the assets.

Impairment of Long-Lived Assets

We identify and record impairment losses on long-lived assets used in operations when events and changes in circumstances indicate that the carrying amount of an asset might not be recoverable, but not less than annually. Recoverability is measured by comparison of the anticipated future net undiscounted cash flows to the related assets’ carrying value. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset.

Research and Development

Research and development costs include expenses paid to outside development consultants and compensation related expenses for our engineering staff. Research and development costs are expensed as incurred.

Income Taxes

We account for income taxes using the asset and liability method. The asset and liability method requires the recognition of deferred tax assets and liabilities for expected future tax consequences of temporary differences that currently exist between the tax basis and financial reporting basis of our assets and liabilities. We calculate current and deferred tax provisions based on estimates and assumptions that could differ from actual results reflected on the income tax returns filed during the following years. Adjustments based on filed returns are recorded when identified in the subsequent years. The effect on deferred taxes for a change in tax rates is recognized in income in the period that the tax rate change is enacted. In assessing our deferred tax assets, we consider whether it is more likely than not that all or some portion of the deferred tax assets will not be realized.

A valuation allowance is provided for deferred income tax assets when, in our judgment, based upon currently available information and other factors, it is more likely than not that all or a portion of such deferred income tax assets will not be realized. The determination of the need for a valuation allowance is based on an on-going evaluation of current information including, among other things, historical operating results, estimates of future earnings in different taxing jurisdictions and the expected timing of the reversals of temporary differences. We believe the determination to record a valuation allowance to reduce a deferred income tax asset is a significant accounting estimate because it is based, among other things, on an estimate of future taxable income in the United States and certain other jurisdictions, which is susceptible to change and may or may not occur, and because the impact of adjusting a valuation allowance may be material. In determining when to release the valuation allowance established against our net deferred income tax assets, we consider all available evidence, both positive and negative. Consistent with our policy, and because of our history of operating losses, we do not currently recognize the benefit of all our deferred tax assets, including tax loss carry forwards, that may be used to offset future taxable income. We continually assess our ability to generate sufficient taxable income during future periods in which our deferred tax assets may be realized. If and when we believe it is more likely than not that we will recover our deferred tax assets, we will reverse the valuation allowance as an income tax benefit in our statements of operations.

We account for our uncertain tax positions in accordance with U.S. GAAP. The purpose of this method is to clarify accounting for uncertain tax positions recognized. The U.S. GAAP method of accounting for uncertain tax positions utilizes a two-step approach to evaluate tax positions. Step one, recognition, requires evaluation of the tax position to determine if based solely on technical merits it is more likely than not to be sustained upon examination. Step two, measurement, is addressed only if a position is more likely than not to be sustained. In step two, the tax benefit is measured as the largest amount of benefit, determined on a cumulative probability basis, which is more likely than not to be realized upon ultimate settlement with tax authorities. If a position does not meet the more likely than not threshold for recognition in step one, no benefit is recorded until the first subsequent period in which the more likely than not standard is met, the issue is resolved with the taxing authority, or the statute of limitations expires. Positions previously recognized are derecognized when we subsequently determine the position no longer is more likely than not to be sustained. Evaluation of tax positions, their technical merits, and measurements using cumulative probability are highly subjective management estimates. Actual results could differ materially from these estimates. We include interest and penalties, if any, in income tax expense. During the years ended December 31, 2017, 2016 and 2015, income tax expense included interest and penalties of $0, $48 and $0, respectively.

On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (the “Act”). The Act amends the Internal Revenue Code to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. For businesses, the Act reduces the corporate federal tax rate from a maximum of 35% to a 21% rate. The rate reduction will be taking effect on January 1, 2018. Therefore, we applied the tax rate of 21% to the ending balance of federal deferred tax assets, but because we provided a full valuation allowance against our net deferred tax assets, no tax impact is recognized due to the tax rate change.

The Act changes the worldwide territorial tax system. Therefore, the deemed repatriation tax applies to undistributed earnings of certain non-U.S. subsidiaries. The company has no deemed repatriation tax liability because its foreign subsidiaries accumulated earnings is negative. We also assess the tax impact of the Act for 2018 and future years and do not believe there is a need to change our valuation allowance position as of December 31, 2017.

Derivative Instruments

Our Series I Warrants were accounted for as derivative instruments as a result of an anti-dilution provision which, in accordance with U.S. GAAP, prevented them from being considered indexed to our stock and qualified for an exception to derivative accounting. The balance of our Series I Warrants expired during the year ended December 31, 2015.

We recognize derivative instruments as either assets or liabilities on the accompanying Consolidated Balance Sheets at fair value. We record changes in the fair value (i.e., gains or losses) of the derivatives in the accompanying Consolidated Statements of Operations.

Stock-Based Compensation

We account for stock-based compensation using the fair value recognition method in accordance with U.S. GAAP. We recognize these compensation costs net of the applicable forfeiture rate and recognize the compensation costs for only those shares expected to vest on a straight-line basis over the requisite service period of the award, which is generally the vesting term of 4 years. We estimate the forfeiture rate based on our historical experience if any. See Note 6 - Stock-Based Compensation and New Accounting Pronouncements below for additional information concerning our share-based compensation awards.

In addition, as required we record stock and options granted to non-employees at fair value of the consideration received or the fair value of the equity instruments issued as they vest over the performance period.

Earnings per Share

Basic earnings per share are computed by dividing earnings available to common stockholders by the weighted average number of outstanding common shares during the period. Diluted earnings per share is computed by dividing net income by the weighted average number of shares outstanding during the period increased to include the number of additional shares of common stock that would have been outstanding if the potentially dilutive securities had been issued. During 2017, 2016 and 2015 we incurred losses; therefore, the effect of any common stock equivalent would be anti-dilutive during these periods.

Reclassifications

Certain prior year amounts in the accompanying consolidated financial statements have been reclassified to conform to the current year’s presentation.

New Accounting Pronouncements

In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments-Credit Losses (Topic 326) “ASU 2016-13”. The purpose of ASU 2016-13 is to require a financial asset measured at amortized cost basis to be presented at the net amount expected to be collected. Credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. ASU 2016-13 is effective for interim and annual reporting periods beginning after December 15, 2019. We are evaluating the impact this guidance will have on our financial position and statement of operations.

In March 2016, the FASB issued ASU No. 2016-09, Compensation – Stock Compensation (Topic 718) (“ASU 2016-09”), which simplified certain aspects of the accounting for share-based payment transactions, including income taxes, classification of awards and classification in the statement of cash flows. We adopted this ASU in 2017 with the following affects:

•

ASU 2016-09 requires excess tax benefits to be recognized regardless of whether the benefit reduces taxes payable. We had zero excess tax benefits recognized for the year ended December 31, 2017.

•

Certain prior period amounts were reclassified to conform to the current year’s presentation. None of these reclassifications had an impact on reported net income for any of the periods presented. As a result of the implementation of ASU 2016-09, our consolidated statements of cash flow for the years ended December 31, 2016 and 2015 have been restated to reflect the reclassification of $93 and $51, respectively, for payments of taxes on cashless exercise of restricted stock units, previously reported in cash flows from operation activities to the current presentation in cash flows from financing activities.

•

The Company has elected to not estimate forfeitures expected to occur to determine the amount of stock-based compensation cost to be recognized in each period. The guidance relating to forfeitures did not have an impact on our accumulated deficit as of December 31, 2017.

In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires an entity to recognize right-of-use assets and lease liabilities on its balance sheet and disclose key information about leasing arrangements. For public companies, ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period, and requires a modified retrospective adoption, with early adoption permitted. We are evaluating the impact this guidance will have on our financial position and statement of operations.

In May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers (Topic 606) “ASU 2014-09”. ASU 2014-09 was subsequently amended by ASU No. 2016-10 and 2016-12. As amended, Topic 606 supersedes the revenue recognition requirements in Topic 605, Revenue Recognition including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. In addition, the amendments create a new Subtopic 340-40, Other Assets and Deferred Costs—Contracts with Customers. In summary, the core principle of Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. For a public entity, the amendments to ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We will adopt the new revenue standards in our first quarter of 2018 utilizing the modified retrospective transition method. We expect the adoption of the standard to result in an approximate $2,500 decrease in accumulated deficit and a $2,500 decrease in deferred revenue in our consolidated balance sheet. The new revenue standards are not expected to have a material impact on the amount and timing of revenue recognized in our consolidated financial statements.

Commitments, contingencies and Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Commitments, contingencies and Related Party Transactions [Abstract]
Commitments, contingencies and Related Party Transactions	Note 4 − Commitments, contingencies and Related Party Transactions We lease our offices under an operating lease with a third party expiring in October 2019. We recognize rent expense on a straight-line basis over the term of the lease. Rent expense was $56, for each of the years ended December 31, 2017, 2016 and 2015. Future minimum rents due under the lease total $56 in 2018, and $46 in 2019 when the lease expires. During 2017, 2016 and 2015 we leased the use of an aircraft from K2 Investment Fund LLC (“LLC”) for business travel for employees of the Company. We incurred approximately $1,240, $772 and $593 in rental fees (including fees and other reimbursements) to the LLC during the year ended December 31, 2017, 2016 and 2015, respectively. Our Chief Executive Officer and Chief Administrative Officer are the managing partners of the LLC and control the equity interests of the LLC. On January 31, 2015, we entered into a 12-month non-exclusive lease with the LLC for use of the plane at a rate of $8 per flight hour, with no minimum usage requirement. The agreement contains other terms and conditions normal in such transactions and can be cancelled by either us or the LLC with 30 days’ notice. The lease renews on an annual basis unless terminated by the lessor or lessee. Neither party has yet exercised their termination rights.

Stock Plan	12 Months Ended
Stock Plan	Dec. 31, 2017
Stock Plan [Abstract]
Stock Plan	Note 5 − Stock Plan We have a stock incentive plan for employees and others called the VirnetX Holding Corporation 2013 Equity Incentive Plan (the “Plan”), which has been approved by our stockholders. To the extent that any award should expire, become un-exercisable or is otherwise forfeited, the shares subject to such award will again become available for issuance under the 2013 Plan. The 2013 Plan provides for the granting of stock options and restricted stock purchase rights (“RSU”) to our employees and consultants. Stock options granted under the 2013 Plan may be incentive stock options or nonqualified stock options. Incentive stock options (“ISO”) may only be granted to our employees (including officers and directors). Nonqualified stock options (“NSO”) and stock purchase rights may be granted to our employees and consultants. The 2013 Plan will expire in 2023. Options may be granted under the 2013 Plan with an exercise price determined by our Board of Directors, or a duly appointed committee thereof, provided, however, that the exercise price of an option granted to any employee shall be not less than 100% of the fair market value at the date of grant in the case of ISO or 85% of the fair market value at the date of grant in the case of an NSO. The exercise price of an ISO or NSO granted to one of our Named Executive Officers shall not be less than 100% fair market value of the shares at the date of grant and the exercise price of an ISO granted to a 10% shareholder shall not be less than 110% of the fair market value of the shares on the date of grant. Stock options granted under the 2013 Plan typically vest over four years and have a 10-year term. All RSUs are considered to be granted at the fair value of our stock on the date of grant because they have no exercise price. RSUs typically vest over four years. At December 31, 2017, there were 2,928,562 shares available for grant under the 2013 Plan.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Stock Based Compensation [Abstract]

Stock Based Compensation

Note 6 − Stock-Based Compensation

The following tables summarize information about stock-options and RSUs outstanding at December 31, 2017:

Options Outstanding							Options Vested and Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price
$ 0.24- 1.58		771,045		1.26	$	1.16		771,045		1.26	$	1.16
$ 1.74- 6.95		3,113,396		8.04		4.27		1,134,677		5.86		4.63
$ 14.52- 35.25		1,253,625		4.71		23.16		1,223,510		4.67		23.35
		5,138,066		6.21	$	8.41		3,129,233		4.26	$	11.09

The following tables summarize activity under the Plan for the indicated periods:

	Options
	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2014		4,489,028		$	9.33		—	$	—
Options granted		694,000			4.47		—		—
Options exercised		(143,100	)		1.15		—		—
Options cancelled		(40,000	)		25.61		—		—
Outstanding at December 31, 2015		4,999,928		$	8.76		—	$	—
Options granted		429,000			4.77		—		—
Options exercised		(50,357	)		0.40		—		—
Outstanding at December 31, 2016		5,378,571		$	8.52		—	$	—
Options granted		1,613,500			4.06		—		—
Options exercised		(12,500	)		1.74		—		—
Options cancelled		(1,841,505	)		4.71		—		—
Outstanding at December 31, 2017		5,138,066		$	8.41		6.21	$	2,529
Options exercisable at December 31, 2017		3,129,233		$	11.09		4.26	$	2,271

	RSUs
	Number of RSUs			Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
Outstanding at December 31, 2014		310,394		$	19.74	$	—
RSUs granted		162,665			5.57		—
RSUs vested		(113,103	)		20.11		—
Outstanding at December 31, 2015		359,956		$	13.22	$	—
RSUs granted		219,331			4.75		—
RSUs vested		(155,852	)		15.27		—
Outstanding at December 31, 2016		423,435		$	8.08	$	—
RSUs granted		220,664			3.83		—
RSUs vested		(174,438	)		10.47		—
Outstanding at December 31, 2017		469,661		$	5.19	$	—

Intrinsic value is calculated as the difference between the per-share market price of our common stock on the last trading day of 2017, which was $3.70, and the exercise price of the options. For options exercised, the intrinsic value is the difference between market price and the exercise price on the date of exercise. We received cash proceeds of $22, $20 and $165 from stock options exercised in 2017, 2016 and 2015, respectively. The total intrinsic value of options exercised was $25, $91 and $203 during the years ended December 31, 2017, 2016 and 2015, respectively. For RSUs vested, the intrinsic value is the difference between market price and the vested price on the date of vest. The total intrinsic value of the RSUs vested was zero during the year ended December 31, 2017.

Stock-based compensation expense is included in general and administrative expense for each period as follows:

Stock-Based Compensation by Type of Award	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2015
Stock options	$	2,446	$	3,436	$	4,939
RSUs		1,540		1,962		2,336
Total stock-based compensation expense	$	3,986	$	5,398	$	7,275

As of December 31, 2017, there was $6,086 of unrecognized stock-based compensation expense expected to be recognized related to unvested employee stock options and $1,767 of unrecognized stock-based compensation expense to be recognized related to unvested RSUs. These costs are expected to be recognized over a weighted-average period of 3.11 and 2.43 years, respectively.

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted average assumptions:

	Year Ended December 31, 2017	Year Ended December 31, 2016	Year Ended December 31, 2015
Expected stock price volatility	84.91%	79.6%	82%
Risk-free interest rate	1.94%	1.85%	2.12%
Expected life term (in years)	6.08 years	6.03 years	6.07 years
Expected dividends	0%	0%	0%

Based on the Black-Scholes option pricing model, the weighted average estimated fair value of employee stock options granted was $2.93, $3.25 and $3.17 per share during the years ended December 31, 2017, 2016 and 2015, respectively.

The expected life was determined using the simplified method outlined in ASC 718, “Compensation - Stock Compensation”, taking the average of the vesting term and the contractual term of the option. Expected volatility of the stock options was based upon historical data and other relevant factors, such as the volatility of comparable publicly-traded companies at a similar stage of life cycle. We have not provided an estimate for forfeitures because we have had nominal forfeited options and RSUs and believe that all outstanding options and RSUs at December 31, 2017, will vest. In 2017 we adopted a policy not to estimate forfeitures (see Note 2, New Accounting Pronouncements, ASU No. 2016-09).

Common Stock	12 Months Ended
Common Stock	Dec. 31, 2017
Common Stock [Abstract]
Common Stock	Note 8 − Common Stock Each share of common stock has the right to one vote. The holders of common stock are entitled to receive dividends whenever funds are legally available and when declared by our Board of Directors, subject to the prior rights of holders of all classes of stock outstanding having priority rights as to dividends. Our restated articles of incorporation authorize us to issue up to 100,000,000 shares of $.0001 par value common stock. In August 2015, we filed a universal shelf registration statement with the SEC enabling us to offer and sell from time to time up to $100 million of equity, debt or other types of securities. We also entered into an at-the-market (“ATM”) equity offering sales agreement with Cowen & Company, LLC in August 2015, under which we may offer and sell shares of our common stock having an aggregate value of up to $35 million. We have and expect to use proceeds from this offering for GABRIEL product development and marketing, and general corporate purposes, which may include working capital, capital expenditures, other corporate expenses and acquisitions of complementary products, technologies or businesses. As of December 31, 2017, common stock with an aggregate value of up to $8,041 remains available for offer and sale under the ATM agreement. We sold 730,444, 4,760,594 and 835,056 shares of common stock under the ATM program during the years ended December 31, 2017, 2016 and 2015 respectively. The average sales price per common share sold during the year ended December 31, 2017 was $5.19 and the aggregate proceeds from the sales totaled $3,790 during the period. Sales commissions, fees and other costs associated with the ATM transactions totaled $113 for 2017. The average sales price per common share sold during the year ended December 31, 2016 was $4.16 and the aggregate proceeds from the sales totaled $19,791 during the period. Sales commissions, fees and other costs associated with the ATM transactions totaled $594 for 2016. The average sales price per common share sold during the year ended December 31, 2015 was $4.04 and the aggregate proceeds from the sales totaled $3,378 during the period. Sales commissions, fees and other costs associated with the ATM totaled $101 for 2015 (see Note 15 – Subsequent Events).

Equity Warrants

12 Months Ended

Dec. 31, 2017

Equity Warrants [Abstract]

Equity Warrants

Note 9 − Equity Warrants

During the year ended December 31, 2015 we issued warrants (“Advisor Warrants”) for the purchase of 25,000 shares of common stock for $7 per share, which expire in April 2020. The Advisor Warrants were issued for advisory services provided by a third party. Our Advisor Warrants were recorded at fair value on the issuance date and included in Additional Paid in Capital on our Consolidated Balance Sheet. The Advisor Warrants are exercisable by the holder, in whole or in part, until expiration, and may also be net-share-settled. Terms of the warrant agreement include no registration requirements for the underlying common stock and there are no anti-dilution provisions. The fair value at issuance of the warrants was recorded in Prepaid Expenses and Other Current Assets, and is being amortized over the twelve-month life of the service contract, with the expense included in Selling, General and Administrative Expense in our Consolidated Statements of Operations.

Information about the Advisor Warrants outstanding during the twelve months ended December 31, 2017 follows:

Original Number of Warrants Issued	Exercise Price per Common Share	Exercisable at December 31, 2016	Became Exercisable	Exercised	Terminated / Cancelled / Expired	Exercisable at December 31, 2017	Expiration Date
25,000	$7.00	25,000	—	—	—	25,000	April 2020

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Taxes [Abstract]

Income Taxes

Note 11 − Income Taxes

The income tax provision is comprised of the following:

	Year Ended December 31, 2017			Year Ended December 31, 2016			Year Ended December 31, 2015
Current:
Federal	$	—		$	—		$	10
State		(3	)		(133	)		(18	)
Foreign		—			—			—
		(3	)		(133	)		(8	)
Deferred:
Federal		—			—			—
State		—			—			—
Total income tax provision	$	(3	)	$	(133	)	$	(8	)

A reconciliation of the United States federal statutory income tax rate to our effective income tax rate is as follows:

	Year Ended December 31, 2017			Year Ended December 31, 2016			Year Ended December 31, 2015
United States federal statutory rate		35.00	%		35.00	%		35.00	%
State taxes, net of federal benefit		(0.01	)%		(0.31	)%		(0.04	)%
Valuation allowance		(35.94	)%		(35.43	)%		(33.36	)%
Stock options		—			—			(1.62	)%
Prior year true-up		—			(0.06	)%		0.03	%
R&D Credit		1.43	%		0.66	%		0.38	%
Warrants		—			—			(0.14	)%
Other		(0.50	)%		(0.33	)%		(0.29	)%
Effective income tax rate		(0.02	)%		(0.47	)%		(0.04	)%

In 2017, 2016 and 2015, we had pre-tax losses of $17, $28 and $29 million, respectively, which are available for carry forward to offset future taxable income. We made determinations to provide full valuation allowances for our net deferred tax assets at the end of 2017, 2016 and 2015, including NOL carryforwards generated during the years, based on our evaluation of positive and negative evidence, including our history of operating losses and the uncertainty of generating future taxable income that would enable us to realize our deferred tax assets.

Deferred tax assets (liabilities) consist of the following:

	Year Ended December 31, 2017			Year Ended December 31, 2016
Deferred tax assets:
Reserves and accruals	$	963		$	1,063
State tax		—			1
Research and development credits and other credits		1,300			1,092
Net operating loss carry forward		22,448			29,186
Stock based compensation		9,260			13,031
Other		54			88
Total deferred tax assets		34,025			44,461

Valuation allowance		(34,025	)		(44,455	)
Deferred tax assets after valuation allowance		—			6

Deferred tax liability:
Depreciation and amortization		—			(6	)

Total deferred tax liability		—			(6	)

Net deferred tax assets	$	—		$	—

The Act changes the worldwide territorial tax system. Therefore, the deemed repatriation tax applies to undistributed earnings of certain non-U.S. subsidiaries. The company has no deemed repatriation tax liability because its foreign subsidiary’s accumulated earnings is negative. We also assess the tax impact of the Act for 2018 and future years and do not believe there is a need to change our valuation allowance position as of December 31, 2017.

In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of deferred assets will not be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible.

Based on the available objective evidence, management believes it is more likely than not that the net deferred tax assets at December 31, 2017 will not be fully realizable. Accordingly, management has maintained a full valuation allowance against its net deferred tax assets at December 31, 2017. The net change in the total valuation allowance for the 12 months ended December 31, 2017 was a decrease of $10,430. At December 31, 2017, we had federal and state net operating loss carry-forwards of approximately $87,429 and $98,425, respectively, expiring beginning in 2027 for federal and began expiring in 2016, for state. At December 31, 2017, we had federal research and development credit carry-forwards of approximately $1,300, expiring beginning in 2031.

Internal Revenue Code Section 382 places a limitation (the “Section 382 Limitation”) on the amount of taxable income that can be offset by net operating loss carry forwards after a change in control (generally greater than 50% change in ownership) of a loss corporation. California, the state in which our headquarters was once located, has similar rules. Our capitalization described herein may have resulted in such a change. Generally, after a control change, a loss corporation cannot deduct net operating loss carry forwards generated in years prior to the deemed change of control under IRC Section 382 in excess of the Section 382 Limitation.

We are required to recognize the financial statement effects of a tax position when it is more likely than not, based on the technical merits, that the position will be sustained upon examination. As a result, we have provided contingent reserve under ASC 740-10 of $316 at December 31, 2017, and December 31, 2016. Our tax returns are subject to review by various tax authorities. The returns subject to review are those from 2005 forward.

Our policy is to recognize interest and penalties, if any, accrued on any unrecognized tax benefits, as a component of income tax expense. We had no interest or penalties accrued for the year ended December 31, 2017.

A reconciliation of beginning and ending amounts of unrecognized tax benefits follows:

	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2015
Balance at the beginning of the year	$	316	$	316	$	316
Additions based on tax positions related to the current year		—		—		—
Additions for tax positions of prior years		—		—		—
Settlements		—		—		—
Lapse of applicable statute of limitations		—		—		—
Balance at the end of the year	$	316	$	316	$	316

Fair Value Measurement

12 Months Ended

Dec. 31, 2017

Fair Value Measurement [Abstract]

Fair Value Measurement

Note 12 − Fair Value Measurement

We apply fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1 – Quoted prices in active markets for identical assets or liabilities.

Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

The carrying amounts for cash and cash equivalents, investments in certificates of deposit, accounts payable and accrued expenses approximate their fair values due to the short period of time until maturity.

Mutual Funds: Valued at the quoted net asset value (NAV) of shares held.

U.S. Agency securities: Fair value measured at the closing price reported on the active market on which the individual securities are traded.

The following table shows our cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category recorded as cash and cash equivalents of investments available for sale as of December 31, 2017 and 2016 (in thousands):

	December 31, 2017
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Investments Available for Sale
Cash	$	1,972	$	—	$	—		$	1,972	$	1,972	$	—

Level 1:
Mutual funds		616		—		—			616		616
U.S. agency securities		2,001		—		(1	)		2,000		547		1,453
		2,617		—		(1	)		2,616		1,163		1,453
Total	$	4,589	$	—	$	(1	)	$	4,588	$	3,135	$	1,453

	December 31, 2016
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Investments Available for Sale
Cash	$	3,432	$	—	$	—		$	3,432	$	3,432	$	—

Level 1:
Mutual funds		3,195		—		—			3,195		3,195		—
U.S. government securities		1,254		—		—			1,254		—		1,254
U.S. agency securities		7,996		2		(3	)		7,995		—		7,995
		12,445		2		(3	)		12,444		3,195		9,249
Total	$	15,877	$	2	$	(3	)	$	15,876	$	6,627	$	9,249

The maturities of our marketable securities generally range from within one to two years. Actual maturities could differ from contractual maturities due to call or prepayment provisions.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Litigation	12 Months Ended
Litigation	Dec. 31, 2017
Litigation [Abstract]
Litigation	Note 13 − Litigation We have eleven intellectual property infringement lawsuits pending in the United States District Court for the Eastern District of Texas, Tyler Division, and United States Court of Appeals for the Federal Circuit (“USCAFC”). VirnetX Inc. v. Apple, Inc. (Case 6:12-CV-00855-LED) On March 30, 2015, the United States Court for the Eastern District of Texas, Tyler Division, issued an order finding substantial overlap between the remanded portions of the Civil Action Case 6:10-CV-00417-LED (VirnetX vs. Cisco et. al.), and the ongoing Civil Action Case 6:12-CV-00855-LED (VirnetX Inc. v. Apple, Inc.). The court consolidated the two civil actions under Civil Action Case 6:12-CV-00855-LED (VirnetX Inc. v. Apple, Inc.) and designated it as the lead case. The jury trial in this case was held on January 25, 2016. On February 4, 2016, a jury in the United States Court for the Eastern District of Texas, Tyler Division, awarded us $625.6 million in a verdict against Apple Inc. for infringing four of our US patents, marking it the second time a federal jury has found Apple liable for infringing VirnetX’s patented technology. The verdict includes royalties awarded to us based on an earlier patent infringement finding (Case 6:10-CV-00417-LED) against Apple. The jury found that Apple’s modified VPN On-Demand, iMessage and FaceTime services infringed VirnetX’s patents and that Apple’s infringement was willful. In addition to determining the royalty owed by Apple for its prior infringement, this verdict also includes an award based on the jury’s finding that Apple’s modified VPN On Demand, iMessage and FaceTime services have continued to infringe VirnetX’s patents. The post-trial hearing was held on May 25, 2016 in the United States Court for the Eastern District of Texas, Texarkana Division. On July 29, 2016, the court issued a new order, vacating its previous orders consolidating the cases (Case No. 6:10-cv-417, Docket No. 878 (“Apple I case”); Case No. 6:12-cv-855, Docket No. 220 (“Apple II case”)), ordering that the two cases be retried separately, and setting the retrial date for Apple I case with jury selection to begin on September 26, 2016. The court also ordered that the issue of willfulness in both cases is bifurcated and that the Apple II case will be retried after Apple I case. Events and developments subsequent to the order from the court are described to support Apple I and Apple II matters. VirnetX Inc. v. Cisco Systems, Inc. et al. (Case 6:10-CV-00417-LED) (“Apple I”) On August 11, 2010, we initiated a lawsuit by filing a complaint against Aastra USA. Inc. (“Aastra”), Apple, Cisco Systems, Inc. (“Cisco”), and NEC Corporation (“NEC”) in the United States District Court for the Eastern District of Texas, Tyler Division, pursuant to which we alleged that these parties infringe on certain of our patents. We sought damages and injunctive relief. Aastra and NEC agreed to sign license agreements with us and we agreed to drop all the accusations of infringement against them. At the pre-trial hearing, the judge decided to conduct separate jury trial for each defendant, and try only the case against Apple on the scheduled trial date. The jury trial of our case against Cisco was held on March 4, 2013. The jury in our case against Cisco came back with a verdict of non-infringement also determined that all our patents-in-suit patents are not invalid. Our motions for a new trial and Cisco’s infringement of certain VirnetX patents were denied and the case against Cisco was closed. The jury trial of our case against Apple was held on October 31, 2012. On November 6, 2012, a jury in the United States Court for the Eastern District of Texas, Tyler Division, awarded us over $368 million in a verdict against Apple for infringing four of our patents. On February 26, 2013, the court issued its Memorandum Opinion and Order regarding post-trial motions resulting from the prior jury verdict denying Apple’s motion to reduce the damages awarded by the jury for past infringement. The Court further denied Apple’s request for a new trial on the liability and damages portions of the verdict and granted our motions for pre-judgment interest, post-judgment interest, and post-verdict damages to date. The Court ordered that Apple pay $34 thousand in daily interest up to final judgment and $330 thousand in daily damages for infringement up to final judgment for certain Apple devices included in the verdict. The Court denied our request for a permanent injunction and severed the future infringement portion into its own separate proceedings under Case 6:13-CV-00211-LED. On July 3, 2013, Apple filed an appeal of the judgment dated February 27, 2013 and order dated June 4, 2013 denying Apple’s motion to alter or amend the judgment to the USCAFC. On September 16, 2014, USCAFC issued their opinion, affirming the jury’s finding that all 4 of our patents are valid, confirming the jury’s finding of infringement of VPN on Demand under many of the asserted claims of our ‘135 and ‘151 patents, and confirming the district’s court’s decision to allow evidence concerning our licenses and royalty rates in connection with the determination of damages. In its opinion, the USCAFC also vacated the jury’s damages award and the district court’s claim construction with respect to parts of our ‘504 and ‘211 patents and remanded the damages award and determination of infringement with respect to FaceTime –for further proceedings consistent with its opinion. On October 16, 2014, we filed a petition with the USCAFC, requesting a rehearing and rehearing en banc of the Federal Circuit’s September 14, 2014, decision concerning VirnetX’s litigation against Apple Inc. On December 16, 2014, USCAFC denied our petition requesting a rehearing and rehearing en banc of the Federal Circuit’s September 14, 2014, decision and remanded the case back to the Eastern District of Texas, Tyler Division, for further proceedings consistent with its opinion. On February 25, 2015, USCAFC granted Apple’s motions to lift stay of proceedings and vacate Case 6:13-CV-00211-LED. On March 30, 2015, the court issued an order finding substantial overlap between the remanded portions of this case and the ongoing Civil Action Case 6:12-CV-00855-LED (VirnetX Inc. v. Apple, Inc.). The court consolidated the two civil actions under Civil Action Case 6:12-CV-00855-LED (VirnetX Inc. v. Apple, Inc.) and designated it as the lead case. On July 29, 2016, the court issued a new order, vacating its previous orders consolidating the cases Apple I case and Apple II case, ordering that the two cases be retried separately, and setting the retrial date for Apple I case with jury selection to begin on September 26, 2016. The court also ordered that the issue of willfulness in both cases is bifurcated and that the Apple II will be retried after Apple I case. The jury trial in this case was held on September 26, 2016. On September 30, 2016, a Jury in the United States Court for the Eastern District of Texas, Tyler Division, in the case VirnetX Inc., et al. v. Apple Inc., No. Apple I, has awarded VirnetX $302.4 million in a verdict against Apple for infringing four VirnetX patents, marking the third time a federal jury has found Apple liable for infringing VirnetX’s patented technology. The verdict includes royalties awarded to VirnetX, for unresolved issues in the Apple I case, remanded back from the USCAFC, related to (1) damages owed to VirnetX for infringement by Apple’s original VPN-on-Demand (VOD) and (2) the alleged infringement by Apple’s original FaceTime product, under the new claim construction of “secure communication link” pertaining to the ’504 and ’211 patents by the USCAFC, and the damages associated with that infringement. The hearing on all the post-trial motions was held on November 22, 2016. On September 29, 2017, the United States District Court for the Eastern District of Texas, Tyler Division, entered Final Judgement and issued its Memorandum Opinion and Order regarding post-trial motions resulting from the prior $302.4 million jury verdict for VirnetX in the Apple I case. In the Order, the Court denied all of Apple’s post-trial motions including motion for judgment as a matter of law of non-infringement, motion for judgment as a matter of law on damages, motion for a new trial on infringement, and motion for a new trial on damages. The Court granted all VirnetX’s post-trial motions including motion for willful infringement and enhanced the royalty rate during the willfulness period by 50 percent, from $1.20 to $1.80 per device, awarding VirnetX, enhanced damages in the amount of $41.3 million against Apple thereby, granting VirnetX a total sum of $343.7 million in pre-interest damages. The Court also awarded costs, certain attorneys’ fees, and prejudgment interest to VirnetX, and directed the parties to meet and confer regarding these amounts. On October 13, 2017, having met and conferred and having reached agreements on all amounts, parties jointly filed a motion asking the Court to grant VirnetX an additional sum in the amount of $96 million in agreed Bill of Costs, Attorneys’ Fees, and Prejudgment Interest. The Final Judgement is only subject to appeal stemming from new issues unresolved in the Apple I case, remanded back from the United States Court of Appeals for the Federal Circuit. The total Final Judgement amount including Jury Verdict, Willful Infringement, Interest, Costs and Attorney Fees is $439.7 million. On October 27, 2017 Apple filed its notice of appeal of the Final Judgment entered on September 29, 2017 to the United States Court of Appeals for the Federal Circuit. This case has now been closed and events and developments subsequent to the notice of appeal are described below under VirnetX Inc. v. Cisco Systems, Inc. (USCAFC Case 18-1197-CB) (Appeal of Apple I Case). VirnetX Inc. v. Apple, Inc. (Case 6:12-CV-00855-LED) (“Apple II”) On November 6, 2012, we filed a complaint against Apple in the United States District Court for the Eastern District of Texas, Tyler Division for willfully infringing four of our patents, U.S. Patent Nos. 6,502,135, 7,418,504, 7,921,211 and 7,490,151, and seeking both an unspecified amount of damages and injunctive relief. The accused products include the iPhone 5, iPod Touch 5^th Generation, iPad 4^th Generation, iPad mini, and the latest Macintosh computers. Due to their release dates, these products were not included in the previous lawsuit that concluded with a Jury verdict on November 6, 2012 that was subsequently upheld by the United States District Court for the Eastern District of Texas, Tyler Division, on February 26, 2013. On July 1, 2013, we filed a consolidated and amended complaint to include U.S. Patent No. 8,051,181 and consolidate Civil Action No. 6:11-cv-00563-LED. On August 27, 2013, we filed an amended complaint including allegations of willful infringement related to U.S. Patent No. 8,504,697 seeking both damages and injunctive relief. The Markman hearing in this case was held on May 20, 2014 and on August 8, 2014, issued its Markman Order, denying Apple’s motion for summary judgment of indefiniteness, in which Apple alleged that some of the disputed claims terms in the patents asserted by us were invalid for indefiniteness. In a separate order, the court granted in part and denied in part our motion for partial summary judgment on Apple’s invalidity counterclaims, precluding Apple from asserting invalidity as a defense against infringement of the claims that were tried before a jury in our prior litigation against Apple (VirnetX vs. Cisco et. al., Case 6:10-CV-00417-LED). The jury trial in this case was scheduled for October 13, 2015. On March 30, 2015, the court issued an order finding substantial overlap between this case and the remanded portions of Case 6:10-CV-00417-LED (VirnetX vs. Cisco et. al.). The court consolidated the two civil actions under Civil Action Case 6:12-CV-00855-LED (VirnetX Inc. v. Apple, Inc.) and designated it as the lead case. On July 29, 2016, the court issued a new order, vacating its previous orders consolidating the cases Apple I case and Apple II case, ordering that the two cases be retried separately, and setting the retrial date for Apple I case with jury selection to begin on September 26, 2016. The court also ordered that the issue of willfulness in both cases is bifurcated and that the Apple II will be retried after Apple I case. On September 29, 2017, the Court issued an order denying Apple’s Motion to Stay. The Court ordered the parties to meet and confer and file a joint motion with a proposed trial date by October 13, 2017. The parties have met, conferred and filed a joint motion on the proposed trial dates. On November 9, 2017, the court issued its order setting this case for jury selection on April 2, 2018 in Tyler, Texas. On January 5, 2018, Apple filed a Petition for Writ of Mandamus with the USCAFC requesting the court to stay the upcoming limited retrial of the Apple II pending the USCAFC’s decision in related consolidated appeal VirnetX Inc. v. Apple Inc., Cases 2017-1591. On February 22, 2018, the USCAFC issued its order denying Apple’s Petition for Writ of Mandamus. The Apple II case is proceeding on schedule for jury selection on April 2, 2018 per the district court’s order. VirnetX Inc. v. Cisco Systems, Inc. (USCAFC Case 18-1197-CB) (Appeal of Apple I Case) On October 27, 2017 Apple filed its notice of appeal of the Final Judgment entered on September 29, 2017 to the United States Court of Appeals for the Federal Circuit. On January 5, 2018, Apple filed a motion requesting a stay of the briefing schedule in this appeal pending this court’s decision in related consolidated appeal VirnetX Inc. v. Apple Inc., Cases 2017-1591. On January 24, 2018, USCAFC denied Apple’s motion requesting a stay of the briefing schedule and ordered Apple to file its opening brief no later than March 19, 2018. VirnetX Inc. v. Apple, Inc. (Case 15-1934) On July 10, 2015, we filed appeals with the USCAFC, appealing the invalidity findings by the United States Patent and Trademark Office, Patent Trial and Appeal Board (“PTAB”) in IPR2014-00237 and IPR2014-00238, related to U.S. Patent No. 8,504,697. The oral arguments in this case were heard on November 7, 2016. On December 9, 2016, the USCAFC affirmed the PTAB based on the grounds discussed in IPR2014-00238. We are currently evaluating our options in this case. VirnetX Inc. v. Apple, Inc. (Case 16-1211) On September 28, 2015, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in IPR2014-00403 and IPR2014-00404 and on October 22, 2015 for IPR2014-00481 and IPR2014-00482 involving our U.S. Patent Nos. 7,188,180, and 7,987,274. The oral arguments in this case were heard on November 7, 2016. On December 9, 2016, the USCAFC affirmed the PTAB based on the grounds discussed in IPR2014-00403 and IPR2014-00481. We are currently evaluating our options in this case. VirnetX Inc. v. Apple, Inc. (Case 16-1480) On November 30, 2015, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in inter-partes reexamination no. 95/001,949 related to U.S. Patent No. 8,051,181. The oral arguments in this case were heard on November 7, 2016. On December 9, 2016, the USCAFC affirmed the PTAB based on certain grounds. We are currently evaluating our options in this case. VirnetX Inc. v. Apple, Inc. (Case 16-119) On March 4, 2016, we filed a petition for writ of mandamus with the USCAFC, requesting the USCAFC’s intervention to revoke the PTAB’s decision joining Apple to IPR2015-01046 and IPR2015-01047, related to U.S. Patent Nos. 6,502,135 and 7,490,151. On March 18, 2016, the USCAFC denied the petition without prejudice to us raising the arguments on appeal after the PTAB’s final decisions. We are currently evaluating our options in this case. VirnetX Inc. v. Apple, Inc. (Case 17-1131) On October 31, 2016, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in IPR2015-00810 and IPR2015-00812, on November 9, 2016 for IPR2015-00811, and on November 28, 2016 for IPR2015-00866, IPR2015-00868, IPR2015-00870 and IPR2015-00871 involving our U.S. Patent Nos.8,868,705, 8,850,009, 8,458,341, 8,516,131, and 8,560,705. These appeals have been consolidated. The briefing in these appeals has been concluded; the oral argument were held on March 5, 2018. We are awaiting the courts ruling in this matter. VirnetX Inc. v. The Mangrove Partners (Case 17-1368) On December 16, 2016, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in IPR2015-01046, and on December 20, 2016 for IPR2015-1047, involving our U.S. Patent Nos. 6,502,135, and 7,490,151. These appeals also involve Apple, Inc. and one of them involves Black Swamp IP, LLC. On April 27, 2017, the USCAFC stayed these appeals pending the USCAFC’s en banc decision in Wi-Fi One, LLC v. Broadcom Corporation, No. 2015-1944. The stay was lifted on January 31, 2018, and briefing is now ongoing. VirnetX Inc. v. Apple Inc., Cisco Systems, Inc. (Case 17-1591) On February 7, 2017, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in inter-partes reexamination nos. 95/001,788, 95/001,789, and 95/001,856 related to our U.S. Patent Nos. 7,921,211 and 7,418,504. These appeals have been consolidated. The briefing in these appeals has been concluded; the oral arguments have not yet been scheduled. VirnetX Inc. v. Apple Inc. (Case 17-2490) On August 23, 2017, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in IPR2016-00331 and IPR2016-00332 involving our U.S. Patent No. 8,504,696. These appeals have been consolidated. The briefing in these appeals has been concluded; the oral arguments have not yet been scheduled. In re VirnetX Inc. (Case 17-2593) On September 22, 2017, we filed appeals with the USCAFC, appealing the invalidity findings by the PTAB in IPR2016-00693 and IPR2016-00957 involving our U.S. Patent Nos. 7,418,504 and 7,921,211. These appeals have been consolidated. The briefing in these appeals is ongoing. The entity that initiated the IPRs, Black Swamp IP, LLC, indicated on October 18, 2017, that it would not participate in the appeals. On November 27, 2017, the United States Patent and Trademark Office indicated that it would intervene in the appeals. On January 19, 2018, the USCAFC stayed these appeals pending the USCAFC’s decision in Case 17-1591. One or more potential intellectual property infringement claims may also be available to us against certain other companies who have the resources to defend against any such claims. Although we believe these potential claims are worth pursuing, commencing a lawsuit can be expensive and time-consuming, and there is no assurance that we will prevail on such potential claims. In addition, bringing a lawsuit may lead to potential counterclaims which may preclude our ability to commercialize our initial products, which are currently in development. Currently, we are not a party to any other pending legal proceedings, and are not aware of any proceeding threatened or contemplated against us by any governmental authority or other party.

Quarterly Financial Information (unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information (unaudited) [Abstract]

Quarterly Financial Information (unaudited)

Note 14 − Quarterly Financial Information (unaudited)

	First			Second			Third			Fourth
				(in thousands except per share)
2017
Revenue	$	375		$	396		$	375		$	401
Loss from operations	$	(3,906	)	$	(3,811	)	$	(3,562	)	$	(6,042	)
Net loss	$	(3,894	)	$	(3,798	)	$	(3,552	)	$	(6,034	)
Basic earnings (loss) per common share	$	(0.07	)	$	(0.07	)	$	(0.06	)	$	(0.10	)
Diluted earnings (loss) per common share	$	(0.07	)	$	(0.07	)	$	(0.06	)	$	(0.10	)

	First			Second			Third			Fourth
				(in thousands except per share)
2016
Revenue	$	375		$	398		$	375		$	402
Loss from operations	$	(8,618	)	$	(5,353	)	$	(7,287	)	$	(7,247	)
Net loss	$	(8,610	)	$	(5,337	)	$	(7,387	)	$	(7,235	)
Basic earnings (loss) per common share	$	(0.16	)	$	(0.10	)	$	(0.13	)	$	(0.12	)
Diluted earnings (loss) per common share	$	(0.16	)	$	(0.10	)	$	(0.13	)	$	(0.12	)

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2017
Subsequent Event [Abstract]
Subsequent Event	Note 15 – Subsequent Event On March 8, 2018, we amended our August 20, 2015 equity offering sales agreement (“Amended Agreement”) with Cowen and Company, LLC (“Cowen”), whereby the maximum aggregate value of the Company’s common stock (“Shares”) we may offer and sell, from time to time, was increased from $35,000,000 to $50,000,000. The Company intends to use the proceeds of this offering for Gabriel product development and marketing, and general corporate purposes, which may include working capital, capital expenditures, other corporate expenses and acquisitions of complementary products, technologies or businesses. Under the Amended Agreement, Cowen may sell Shares in an “at-the-market” offering (“ATM”) as defined in Rule 415 promulgated under the Securities Act of 1933, including sales made directly on the NYSE American, LLC, on any other existing trading market for the Shares, or to or through a market maker. In addition, under the Amended Agreement, Cowen may sell the Shares by any other method permitted by law, including private offerings. Subject to the terms and conditions of the Amended Agreement, Cowen will act as sales agent and use commercially reasonable efforts to sell on our behalf all the shares of common stock requested to be sold by us, consistent with its normal trading and sales practices, on mutually agreed terms between Cowen and us. Between January 1, 2018 and March 14, 2018, we sold 1,749,185 shares of common stock under the ATM program. The average sales price per common share sold was $4.02 and the aggregate proceeds from the sales totaled $7,032. Sales commissions, fees and other costs associated with the ATM transactions totaled $211.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Summary of Significant Accounting Policies [Abstract]

Use of Estimates

Basis of Consolidation

The consolidated financial statements include the accounts of VirnetX Holding Corporation and our wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated.

Revenue Recognition

Revenue Recognition (see Note 2 -New Accounting Pronouncements - ASU No. 2014-09, Revenue from Contracts with Customers)

•

Deferred Revenue

Activity under the August 2013 Contract Settlement was as follows:

	2017		2016		2015
Deferred Revenue, beginning of year	$	4,000	$	3,000	$	2,000
Payment received		—		2,500		2,500
Less: Amount amortized as revenue		1,500		1,500		1,500
Deferred Revenue, end of year	$	2,500	$	4,000	$	3,000

Royalty Expense

Cash and Cash Equivalents

Prepaid Expenses and Other Current Assets

Investments

Property and Equipment

Concentration of Credit Risk and Other Risks and Uncertainties

Fair Value

The carrying amounts of our financial instruments, including cash equivalents, accounts payable, and accrued liabilities, approximate fair value because of their generally short maturities.

Intangible Assets

Impairment of Long-Lived Assets

Research and Development

Income Taxes

Derivative Instruments

Stock-Based Compensation

Earnings per Share

Reclassifications

Certain prior year amounts in the accompanying consolidated financial statements have been reclassified to conform to the current year’s presentation.

New Accounting Pronouncements

•

ASU 2016-09 requires excess tax benefits to be recognized regardless of whether the benefit reduces taxes payable. We had zero excess tax benefits recognized for the year ended December 31, 2017.

•

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock Based Compensation [Abstract]

Information about Stock Options Outstanding

The following tables summarize information about stock-options and RSUs outstanding at December 31, 2017:

Options Outstanding							Options Vested and Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price
$ 0.24- 1.58		771,045		1.26	$	1.16		771,045		1.26	$	1.16
$ 1.74- 6.95		3,113,396		8.04		4.27		1,134,677		5.86		4.63
$ 14.52- 35.25		1,253,625		4.71		23.16		1,223,510		4.67		23.35
		5,138,066		6.21	$	8.41		3,129,233		4.26	$	11.09

Stock Option Activity

The following tables summarize activity under the Plan for the indicated periods:

	Options
	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2014		4,489,028		$	9.33		—	$	—
Options granted		694,000			4.47		—		—
Options exercised		(143,100	)		1.15		—		—
Options cancelled		(40,000	)		25.61		—		—
Outstanding at December 31, 2015		4,999,928		$	8.76		—	$	—
Options granted		429,000			4.77		—		—
Options exercised		(50,357	)		0.40		—		—
Outstanding at December 31, 2016		5,378,571		$	8.52		—	$	—
Options granted		1,613,500			4.06		—		—
Options exercised		(12,500	)		1.74		—		—
Options cancelled		(1,841,505	)		4.71		—		—
Outstanding at December 31, 2017		5,138,066		$	8.41		6.21	$	2,529
Options exercisable at December 31, 2017		3,129,233		$	11.09		4.26	$	2,271

Restricted Stock Units Activity

	RSUs
	Number of RSUs			Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value
Outstanding at December 31, 2014		310,394		$	19.74	$	—
RSUs granted		162,665			5.57		—
RSUs vested		(113,103	)		20.11		—
Outstanding at December 31, 2015		359,956		$	13.22	$	—
RSUs granted		219,331			4.75		—
RSUs vested		(155,852	)		15.27		—
Outstanding at December 31, 2016		423,435		$	8.08	$	—
RSUs granted		220,664			3.83		—
RSUs vested		(174,438	)		10.47		—
Outstanding at December 31, 2017		469,661		$	5.19	$	—

Stock-Based Compensation by Type of Award

Stock-based compensation expense is included in general and administrative expense for each period as follows:

Stock-Based Compensation by Type of Award	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2015
Stock options	$	2,446	$	3,436	$	4,939
RSUs		1,540		1,962		2,336
Total stock-based compensation expense	$	3,986	$	5,398	$	7,275

Fair Value Assumptions

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted average assumptions:

	Year Ended December 31, 2017	Year Ended December 31, 2016	Year Ended December 31, 2015
Expected stock price volatility	84.91%	79.6%	82%
Risk-free interest rate	1.94%	1.85%	2.12%
Expected life term (in years)	6.08 years	6.03 years	6.07 years
Expected dividends	0%	0%	0%

Equity Warrants (Tables)

12 Months Ended

Dec. 31, 2017

Equity Warrants [Abstract]

Information about Warrants Outstanding

Information about the Advisor Warrants outstanding during the twelve months ended December 31, 2017 follows:

Original Number of Warrants Issued	Exercise Price per Common Share	Exercisable at December 31, 2016	Became Exercisable	Exercised	Terminated / Cancelled / Expired	Exercisable at December 31, 2017	Expiration Date
25,000	$7.00	25,000	—	—	—	25,000	April 2020

- 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

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes [Abstract]

Components of Income Tax Expense (Benefit)

The income tax provision is comprised of the following:

	Year Ended December 31, 2017			Year Ended December 31, 2016			Year Ended December 31, 2015
Current:
Federal	$	—		$	—		$	10
State		(3	)		(133	)		(18	)
Foreign		—			—			—
		(3	)		(133	)		(8	)
Deferred:
Federal		—			—			—
State		—			—			—
Total income tax provision	$	(3	)	$	(133	)	$	(8	)

Effective Income Tax Rate Reconciliation

A reconciliation of the United States federal statutory income tax rate to our effective income tax rate is as follows:

	Year Ended December 31, 2017			Year Ended December 31, 2016			Year Ended December 31, 2015
United States federal statutory rate		35.00	%		35.00	%		35.00	%
State taxes, net of federal benefit		(0.01	)%		(0.31	)%		(0.04	)%
Valuation allowance		(35.94	)%		(35.43	)%		(33.36	)%
Stock options		—			—			(1.62	)%
Prior year true-up		—			(0.06	)%		0.03	%
R&D Credit		1.43	%		0.66	%		0.38	%
Warrants		—			—			(0.14	)%
Other		(0.50	)%		(0.33	)%		(0.29	)%
Effective income tax rate		(0.02	)%		(0.47	)%		(0.04	)%

Deferred Tax Assets and Liabilities

Deferred tax assets (liabilities) consist of the following:

	Year Ended December 31, 2017			Year Ended December 31, 2016
Deferred tax assets:
Reserves and accruals	$	963		$	1,063
State tax		—			1
Research and development credits and other credits		1,300			1,092
Net operating loss carry forward		22,448			29,186
Stock based compensation		9,260			13,031
Other		54			88
Total deferred tax assets		34,025			44,461

Valuation allowance		(34,025	)		(44,455	)
Deferred tax assets after valuation allowance		—			6

Deferred tax liability:
Depreciation and amortization		—			(6	)

Total deferred tax liability		—			(6	)

Net deferred tax assets	$	—		$	—

Unrecognized Tax Benefits Reconciliation

A reconciliation of beginning and ending amounts of unrecognized tax benefits follows:

	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2015
Balance at the beginning of the year	$	316	$	316	$	316
Additions based on tax positions related to the current year		—		—		—
Additions for tax positions of prior years		—		—		—
Settlements		—		—		—
Lapse of applicable statute of limitations		—		—		—
Balance at the end of the year	$	316	$	316	$	316

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurement [Abstract]

Cash and Available-for-Sale Securities Adjusted Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value by Significant Investment Category

	December 31, 2017
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Investments Available for Sale
Cash	$	1,972	$	—	$	—		$	1,972	$	1,972	$	—

Level 1:
Mutual funds		616		—		—			616		616
U.S. agency securities		2,001		—		(1	)		2,000		547		1,453
		2,617		—		(1	)		2,616		1,163		1,453
Total	$	4,589	$	—	$	(1	)	$	4,588	$	3,135	$	1,453

	December 31, 2016
	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Investments Available for Sale
Cash	$	3,432	$	—	$	—		$	3,432	$	3,432	$	—

Level 1:
Mutual funds		3,195		—		—			3,195		3,195		—
U.S. government securities		1,254		—		—			1,254		—		1,254
U.S. agency securities		7,996		2		(3	)		7,995		—		7,995
		12,445		2		(3	)		12,444		3,195		9,249
Total	$	15,877	$	2	$	(3	)	$	15,876	$	6,627	$	9,249

Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information (unaudited) [Abstract]

Quarterly Financial Information

	First			Second			Third			Fourth
				(in thousands except per share)
2017
Revenue	$	375		$	396		$	375		$	401
Loss from operations	$	(3,906	)	$	(3,811	)	$	(3,562	)	$	(6,042	)
Net loss	$	(3,894	)	$	(3,798	)	$	(3,552	)	$	(6,034	)
Basic earnings (loss) per common share	$	(0.07	)	$	(0.07	)	$	(0.06	)	$	(0.10	)
Diluted earnings (loss) per common share	$	(0.07	)	$	(0.07	)	$	(0.06	)	$	(0.10	)

	First			Second			Third			Fourth
				(in thousands except per share)
2016
Revenue	$	375		$	398		$	375		$	402
Loss from operations	$	(8,618	)	$	(5,353	)	$	(7,287	)	$	(7,247	)
Net loss	$	(8,610	)	$	(5,337	)	$	(7,387	)	$	(7,235	)
Basic earnings (loss) per common share	$	(0.16	)	$	(0.10	)	$	(0.13	)	$	(0.12	)
Diluted earnings (loss) per common share	$	(0.16	)	$	(0.10	)	$	(0.13	)	$	(0.12	)

Formation and Business of the Company (Details) - Patents [Member]	Dec. 31, 2017 Patent
Finite-Lived Intangible Assets [Line Items]
Number of patents and pending applications	185
U.S. [Member]
Finite-Lived Intangible Assets [Line Items]
Number of patents and pending applications	70
Foreign [Member]
Finite-Lived Intangible Assets [Line Items]
Number of patents and pending applications	115

Summary of Significant Accounting Policies (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) Institution	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Patent License Agreements [Abstract]
Threshold period of payment of fees after delivery for fees to be generally presumed not to be fixed or determinable, and for revenue to be deferred and recognized as earned			12 months
Royalty Expense [Abstract]
Royalties expense as a result of royalty agreement with Leidos			$ 0	$ 884	$ 5,265
Prepaid Expense and Other Assets, Current [Abstract]
Prepayment of facility lease for corporate promotional and marketing purposes						$ 4,000
Lease term			10 years
Concentration of Credit Risk and Others Risks and Uncertainties [Abstract]
Number of financial institutions holding company's cash \| Institution			2
Income Taxes [Abstract]
Interest and penalties included in income tax expense			$ 0	$ 48	$ 0
Corporate federal tax rate			35.00%	35.00%	35.00%
Stock-Based Compensation [Abstract]
Option vesting term			4 years
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in deferred revenue			$ (1,500)	$ 1,000	$ 1,000
Minimum [Member]
Property and Equipment [Abstract]
Useful lives			5 years
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives			3 years
Maximum [Member]
Property and Equipment [Abstract]
Useful lives			7 years
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives			15 years
Income Taxes [Abstract]
Corporate federal tax rate			35.00%
Plan [Member]
Income Taxes [Abstract]
Corporate federal tax rate		21.00%
Highly Liquid Debt Investments [Member] \| Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Contractual maturities of investment securities			2 years
August 2013 Contract [Member]
Deferred Revenue [Abstract]
Term of contract			4 years
Contract amount			$ 10,000
Non-refundable cash payment received to date			10,000
Activity under August 2013 contract settlement [Roll Forward]
Deferred Revenue, beginning of period	$ 2,500	$ 2,500	4,000	3,000	2,000
Payment received			0	2,500	2,500
Less: Amount amortized as revenue			1,500	1,500	1,500
Deferred Revenue, end of period			$ 2,500	4,000	3,000
ASU 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prior period reclassification adjustment				$ 93	$ 51
ASU 2016-10 and 12 [Member] \| Forecast [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in accumulated deficit	(2,500)
Decrease in deferred revenue	$ (2,500)

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment [Line Items]
Property and equipment, gross	$ 251	$ 251
Less accumulated depreciation	(244)	(218)
Property and equipment, net	7	33
Depreciation expense	26	28	$ 26
Office Furniture [Member]
Property and Equipment [Line Items]
Property and equipment, gross	79	79
Computer Equipment [Member]
Property and Equipment [Line Items]
Property and equipment, gross	$ 172	$ 172

Commitments, contingencies and Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leased Assets [Line Items]
Rent expense	$ 56	$ 56	$ 56
Future minimum rents due in 2018	56
Future minimum rents due in 2019	$ 46
Term of lease	10 years
Offices [Member]
Operating Leased Assets [Line Items]
Operating lease expiring date	Oct. 31, 2019
K2 Investment Fund LLC [Member] \| Aircraft [Member]
Operating Leased Assets [Line Items]
Rental fees incurred for use of aircraft	$ 1,240	$ 772	$ 593
Term of lease	12 months
Rate of aircraft lease (in dollars per flight hour)	$ 8
Term of notice for cancellation of lease	30 days

Stock Plan (Details)	12 Months Ended
Stock Plan (Details)	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	2,928,562
2013 Plan [Member] \| Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award	10 years
Vesting period	4 years
2013 Plan [Member] \| Stock Options [Member] \| Named Executive Officers [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option granted as percentage of fair market value of shares at date of grant	100.00%
2013 Plan [Member] \| Stock Options [Member] \| 10% Shareholder [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option granted as percentage of fair market value of shares at date of grant	110.00%
2013 Plan [Member] \| Incentive Stock Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option granted as percentage of fair market value of shares at date of grant	100.00%
2013 Plan [Member] \| Nonqualified Stock Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option granted as percentage of fair market value of shares at date of grant	85.00%
2013 Plan [Member] \| Restricted Stock Purchase Rights ("RSU") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

Stock-Based Compensation, Information about Stock Options Outstanding (Details) - Stock Options [Member]	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, number outstanding (in shares) \| shares	5,138,066
Options outstanding, weighted average remaining contractual life	6 years 2 months 16 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 8.41
Options vested and exercisable, number exercisable (in shares) \| shares	3,129,233
Options vested and exercisable, weighted average remaining contractual life	4 years 3 months 4 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	$ 11.09
$0.24 - 1.58 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	0.24
Exercise price range, upper range limit (in dollars per share)	$ 1.58
Options outstanding, number outstanding (in shares) \| shares	771,045
Options outstanding, weighted average remaining contractual life	1 year 3 months 4 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 1.16
Options vested and exercisable, number exercisable (in shares) \| shares	771,045
Options vested and exercisable, weighted average remaining contractual life	1 year 3 months 4 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	$ 1.16
$1.74 - 6.95 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	1.74
Exercise price range, upper range limit (in dollars per share)	$ 6.95
Options outstanding, number outstanding (in shares) \| shares	3,113,396
Options outstanding, weighted average remaining contractual life	8 years 14 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 4.27
Options vested and exercisable, number exercisable (in shares) \| shares	1,134,677
Options vested and exercisable, weighted average remaining contractual life	5 years 10 months 10 days
Options vested and exercisable, weighted average exercise price (in dollars per share)	$ 4.63
$14.52 - 35.25 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	14.52
Exercise price range, upper range limit (in dollars per share)	$ 35.25
Options outstanding, number outstanding (in shares) \| shares	1,253,625
Options outstanding, weighted average remaining contractual life	4 years 8 months 16 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 23.16
Options vested and exercisable, number exercisable (in shares) \| shares	1,223,510
Options vested and exercisable, weighted average remaining contractual life	4 years 8 months 1 day
Options vested and exercisable, weighted average exercise price (in dollars per share)	$ 23.35

Stock-Based Compensation, Summary of Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options, additional disclosures [Abstract]
Per share market price of common stock on last trading day of year (in dollars per share)	$ 3.70
Proceeds from exercise of options	$ 22	$ 20	$ 165
Stock Options [Member]
Options, number of shares [Roll Forward]
Outstanding, beginning of period (in shares)	5,378,571	4,999,928	4,489,028
Options granted (in shares)	1,613,500	429,000	694,000
Options exercised (in shares)	(12,500)	(50,357)	(143,100)
Options cancelled (in shares)	(1,841,505)		(40,000)
Outstanding, end of period (in shares)	5,138,066	5,378,571	4,999,928
Options exercisable, end of period (in shares)	3,129,233
Options, weighted average exercise price [Roll Forward]
Outstanding, beginning of period (in dollars per share)	$ 8.52	$ 8.76	$ 9.33
Options granted (in dollars per share)	4.06	4.77	4.47
Options exercised (in dollars per share)	1.74	0.40	1.15
Options cancelled (in dollars per share)	4.71		25.61
Outstanding, end of period (in dollars per share)	8.41	$ 8.52	$ 8.76
Options exercisable, end of period (in dollars per share)	$ 11.09
Options, additional disclosures [Abstract]
Options outstanding, weighted average remaining contractual life	6 years 2 months 16 days
Options exercisable, weighted average remaining contractual life	4 years 3 months 4 days
Options outstanding, aggregate intrinsic value	$ 2,529
Options exercisable, aggregate intrinsic value	2,271
Proceeds from exercise of options	22	$ 20	$ 165
Total intrinsic value of options exercised	$ 25	$ 91	$ 203
Restricted Stock Units (RSUs) [Member]
RSUs, number of RSUs [Roll Forward]
Outstanding, beginning of period (in shares)	423,435	359,956	310,394
RSUs granted (in shares)	220,664	219,331	162,665
RSUs vested (in shares)	(174,438)	(155,852)	(113,103)
Outstanding, end of period (in shares)	469,661	423,435	359,956
RSUs, weighted average grant date fair value [Abstract]
Outstanding, beginning of period (in dollars per share)	$ 8.08	$ 13.22	$ 19.74
RSUs granted (in dollars per share)	3.83	4.75	5.57
RSUs vested (in dollars per share)	10.47	15.27	20.11
Outstanding, end of period (in dollars per share)	$ 5.19	$ 8.08	$ 13.22
RSUs, aggregate intrinsic value [Abstract]
Outstanding, end of period	$ 0	$ 0	$ 0	$ 0
Total intrinsic value of RSUs vested	$ 0

Stock-Based Compensation, Stock-Based Compensation by Type of Award (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,986	$ 5,398	$ 7,275
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3,986	5,398	7,275
Stock Options [Member]
Compensation cost not yet recognized [Abstract]
Unrecognized stock-based compensation expense expected to be recognized related to non-vested stock options	$ 6,086
Weighted-average period for recognition of unrecognized stock-based compensation expense	3 years 1 month 10 days
Stock Options [Member] \| General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,446	3,436	4,939
Restricted Stock Units (RSUs) [Member]
Compensation cost not yet recognized [Abstract]
Unrecognized stock-based compensation expense expected to be recognized related to non-vested RSUs	$ 1,767
Weighted-average period for recognition of unrecognized stock-based compensation expense	2 years 5 months 5 days
Restricted Stock Units (RSUs) [Member] \| General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,540	$ 1,962	$ 2,336

Stock-Based Compensation, Fair Value Assumptions Used (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair value assumptions used in estimating fair value of each option grant [Abstract]
Expected stock price volatility	84.91%	79.60%	82.00%
Risk-free interest rate	1.94%	1.85%	2.12%
Expected option term	6 years 29 days	6 years 11 days	6 years 25 days
Expected dividends	0.00%	0.00%	0.00%
Options granted, weighted average grant date fair value (in dollars per share)	$ 2.93	$ 3.25	$ 3.17

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Calculation of basic and diluted loss per share [Abstract]
Net loss	$ (6,034)	$ (3,552)	$ (3,798)	$ (3,894)	$ (7,235)	$ (7,387)	$ (5,337)	$ (8,610)	$ (17,278)	$ (28,569)	$ (29,234)
Basic and diluted weighted average number of shares outstanding (in shares)									58,354,397	55,984,825	52,384,494
Basic and diluted loss per share (in dollars per share)									$ (0.30)	$ (0.51)	$ (0.56)

Common Stock (Details)	12 Months Ended
Common Stock (Details)	Dec. 31, 2017 USD ($) Vote $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Aug. 31, 2015 USD ($)	Aug. 20, 2015 USD ($)
Subsidiary, Sale of Stock [Line Items]
Common stock, shares authorized (in shares) \| shares	100,000,000	100,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Common stock, voting rights	Each share of common stock has the right to one vote
Number of votes entitled to each share of common stock \| Vote	1
Common stock, shares authorized (in shares) \| shares	100,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001
Number of shares of common stock sold (in shares) \| shares	730,444	4,760,594	835,056
Universal Shelf Registration Statement [Member] \| Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Securities offered for sale, aggregate value				$ 100,000,000
ATM Agreement [Member] \| Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Securities offered for sale, aggregate value				$ 35,000,000	$ 35,000,000
Aggregate value of common stock available for offer and sale	$ 8,041,000
Number of shares of common stock sold (in shares) \| shares	730,444	4,760,594	835,056
Average sales price per common share (in dollars per share) \| $ / shares	$ 5.19	$ 4.16	$ 4.04
Aggregate proceeds from sales of common stock	$ 3,790,000	$ 19,791,000	$ 3,378,000
Sales commissions, fees and other costs associated with issuance of common stock	$ 113,000	$ 594,000	$ 101,000

Equity Warrants (Details) - $ / shares	12 Months Ended
Equity Warrants (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2015
Information about warrants outstanding [Abstract]
Exercise Price per Common Share (in dollars per share)		$ 3.59
Advisor Warrants [Member]
Warrants [Abstract]
Life of service contract	12 months
Warrants [Member] \| Advisor Warrants [Member]
Information about warrants outstanding [Abstract]
Original Number of Warrants Issued (in shares)	25,000
Exercise Price per Common Share (in dollars per share)	$ 7.00
Exercisable, beginning of period (in shares)	25,000
Became Exercisable (in shares)	0
Exercised (in shares)	0
Terminated/Cancelled/Expired (in shares)	0
Exercisable, end of period (in shares)	25,000
Expiration date	Apr. 30, 2020

Income Taxes, Components of Benefit (Provision) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current [Abstract]
Federal	$ 0	$ 0	$ 10
State	(3)	(133)	(18)
Foreign	0	0	0
Current income taxes	(3)	(133)	(8)
Deferred [Abstract]
Federal	0	0	0
State	0	0	0
Total income tax provision	$ (3)	$ (133)	$ (8)

Income Taxes, Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Tax Rate Reconciliation [Abstract]
United States federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	(0.01%)	(0.31%)	(0.04%)
Valuation allowance	(35.94%)	(35.43%)	(33.36%)
Stock options	0.00%	0.00%	(1.62%)
Prior year true-up	0.00%	(0.06%)	0.03%
R&D Credit	1.43%	0.66%	0.38%
Warrants	0.00%	0.00%	(0.14%)
Other	(0.50%)	(0.33%)	(0.29%)
Effective income tax rate	(0.02%)	(0.47%)	(0.04%)

Income Taxes, Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets [Abstract]
Reserves and accruals		$ 963	$ 1,063
State tax		0	1
Research and development credits and other credits		1,300	1,092
Net operating loss carry forward		22,448	29,186
Stock based compensation		9,260	13,031
Other		54	88
Total deferred tax assets		34,025	44,461
Valuation allowance		(34,025)	(44,455)
Deferred tax assets after valuation allowance		0	6
Deferred tax liability [Abstract]
Depreciation and amortization		0	(6)
Total deferred tax liability		0	(6)
Net deferred tax assets		$ 0	$ 0
Income Tax Disclosure [Line Items]
Corporate federal tax rate		35.00%	35.00%	35.00%
Maximum [Member]
Income Tax Disclosure [Line Items]
Corporate federal tax rate		35.00%
Plan [Member]
Income Tax Disclosure [Line Items]
Corporate federal tax rate	21.00%

Income Taxes, Valuation Allowance, Operating Loss Carryforwards and Tax Credit Carry-forwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Net change in valuation allowance	$ (10,430)
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	17,000	$ 28,000	$ 29,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 87,429
Operating loss carryforwards, expiration dates	Dec. 31, 2027
Federal [Member] \| Research and Development [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 1,300
Federal tax credit carryforward, expiration dates	Dec. 31, 2031
State [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 98,425
Operating loss carryforwards, expiration dates	Dec. 31, 2016

Income Taxes, Income Tax Uncertainties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Accrued interest and penalties	$ 0
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	316	$ 316	$ 316
Additions based on tax positions related to the current year	0	0	0
Additions for tax positions of prior years	0	0	0
Settlements	0	0	0
Lapse of applicable statute of limitations	0	0	0
Balance at the end of the year	$ 316	$ 316	$ 316

Fair Value Measurement, Adjusted Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value by Investment Category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	$ 3,135	$ 6,627	$ 8,726	$ 18,658
Adjusted Cost	2,617	12,445
Unrealized Gains	0	2
Unrealized Losses	(1)	(3)
Fair Value	2,616	12,444
Adjusted Cost	4,589	15,877
Fair Value	4,588	15,876
Investments Available for Sale	$ 2,616	12,444
Minimum [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Maturities of available for sale securities	1 year
Maximum [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Maturities of available for sale securities	2 years
Cash [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	$ 1,972	3,432
Fair Value	1,972	3,432
Cash and Cash Equivalents	1,972	3,432
Mutual Funds [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	616	3,195
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	616	3,195
Investments Available for Sale	616	3,195
U.S. Government Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost		1,254
Unrealized Gains		0
Unrealized Losses		0
Fair Value		1,254
Investments Available for Sale		1,254
US Agency Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Adjusted Cost	2,001	7,996
Unrealized Gains	0	2
Unrealized Losses	(1)	(3)
Fair Value	2,000	7,995
Investments Available for Sale	2,000	7,995
Recurring [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	3,135	6,627
Fair Value	1,453	9,249
Cash and Cash Equivalents	3,135	6,627
Investments Available for Sale	1,453	9,249
Recurring [Member] \| Cash [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	1,972	3,432
Cash and Cash Equivalents	1,972	3,432
Recurring [Member] \| Level 1 [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	1,163	3,195
Fair Value	1,453	9,249
Cash and Cash Equivalents	1,163	3,195
Investments Available for Sale	1,453	9,249
Recurring [Member] \| Level 1 [Member] \| Mutual Funds [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	616	3,195
Fair Value	0	0
Cash and Cash Equivalents	616	3,195
Investments Available for Sale	0	0
Recurring [Member] \| Level 1 [Member] \| U.S. Government Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value		0
Fair Value		1,254
Cash and Cash Equivalents		0
Investments Available for Sale		1,254
Recurring [Member] \| Level 1 [Member] \| US Agency Securities [Member]
Cash and available-for-sale securities adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category [Abstract]
Fair Value	547	0
Fair Value	1,453	7,995
Cash and Cash Equivalents	547	0
Investments Available for Sale	$ 1,453	$ 7,995

Litigation (Details) - Positive Outcome of Litigation [Member]	Oct. 13, 2017 USD ($)	Sep. 29, 2017 USD ($)	Sep. 30, 2016 USD ($) Patent	Jul. 29, 2016 Case	Feb. 04, 2016 USD ($) Patent	Mar. 30, 2015 Action	Feb. 26, 2013 USD ($)	Nov. 06, 2012 USD ($) Patent	Dec. 31, 2017 Lawsuit
Gain Contingencies [Line Items]
Number of intellectual property infringement lawsuits pending \| Lawsuit									11
VirnetX Inc. v. Apple, Inc. (Case 6:12-CV-00855-LED) [Member]
Gain Contingencies [Line Items]
Number of civil actions consolidated by court \| Action						2
Amount of damages awarded in patent infringement case					$ 625,600,000
Number of patents allegedly infringed upon by Apple, Inc. \| Patent					4
Number of cases ordered to be retried by court \| Case				2
VirnetX Inc. v. Cisco Systems, Inc. et al. (Case 6:10-CV-00417-LED) ("Apple I") [Member]
Gain Contingencies [Line Items]
Number of civil actions consolidated by court \| Action						2
Amount of damages awarded in patent infringement case	$ 439,700,000	$ 343,700,000	$ 302,400,000					$ 368,000,000
Number of patents allegedly infringed upon by Apple, Inc. \| Patent			4					4
Number of cases ordered to be retried by court \| Case				2
Amount of interest payment awarded up to final judgment, per day							$ 34,000
Amount of damage infringement payment awarded up to final judgment, per day							$ 330,000
Percentage of enhanced damages awarded during the willfulness period		50.00%
Enhanced damages		$ 41,300,000
Additional amount granted in agreed bill of costs, attorney fees, and prejudgment interest	$ (96,000,000)
VirnetX Inc. v. Cisco Systems, Inc. et al. (Case 6:10-CV-00417-LED) ("Apple I") [Member] \| Minimum [Member]
Gain Contingencies [Line Items]
Royalty rate per device used in calculating infringement damages		1.20
VirnetX Inc. v. Cisco Systems, Inc. et al. (Case 6:10-CV-00417-LED) ("Apple I") [Member] \| Maximum [Member]
Gain Contingencies [Line Items]
Royalty rate per device used in calculating infringement damages		$ 1.80
VirnetX Inc. v. Apple, Inc. (Case 6:12-CV-00855-LED) ("Apple II") [Member]
Gain Contingencies [Line Items]
Number of civil actions consolidated by court \| Action						2
Number of patents allegedly infringed upon by Apple, Inc. \| Patent								4
Number of cases ordered to be retried by court \| Case				2

Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information (unaudited) [Abstract]
Revenue	$ 401	$ 375	$ 396	$ 375	$ 402	$ 375	$ 398	$ 375	$ 1,547	$ 1,550	$ 1,555
Loss from operations	(6,042)	(3,562)	(3,811)	(3,906)	(7,247)	(7,287)	(5,353)	(8,618)	(17,321)	(28,505)	(29,177)
Net loss	$ (6,034)	$ (3,552)	$ (3,798)	$ (3,894)	$ (7,235)	$ (7,387)	$ (5,337)	$ (8,610)	$ (17,278)	$ (28,569)	$ (29,234)
Basic earnings (loss) per common share (in dollars per share)	$ (0.10)	$ (0.06)	$ (0.07)	$ (0.07)	$ (0.12)	$ (0.13)	$ (0.10)	$ (0.16)
Diluted earnings (loss) per common share (in dollars per share)	$ (0.10)	$ (0.06)	$ (0.07)	$ (0.07)	$ (0.12)	$ (0.13)	$ (0.10)	$ (0.16)

Subsequent Event (Details) - Common Stock [Member] - USD ($)	2 Months Ended	12 Months Ended
	Mar. 14, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 08, 2018	Aug. 31, 2015	Aug. 20, 2015
Subsequent Event [Line Items]
Number of shares of common stock sold (in shares)		730,444	4,760,594	835,056
ATM Agreement [Member]
Subsequent Event [Line Items]
Securities offered for sale, aggregate value						$ 35,000,000	$ 35,000,000
Number of shares of common stock sold (in shares)		730,444	4,760,594	835,056
Average sales price per common share (in dollars per share)		$ 5.19	$ 4.16	$ 4.04
Aggregate proceeds from sales of common stock		$ 3,790,000	$ 19,791,000	$ 3,378,000
Sales commissions, fees and other costs associated with issuance of common stock		$ 113,000	$ 594,000	$ 101,000
Subsequent Event [Member] \| ATM Agreement [Member]
Subsequent Event [Line Items]
Securities offered for sale, aggregate value					$ 50,000,000
Number of shares of common stock sold (in shares)	1,749,185
Average sales price per common share (in dollars per share)	$ 4.02
Aggregate proceeds from sales of common stock	$ 7,032,000
Sales commissions, fees and other costs associated with issuance of common stock	$ 211,000

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock issued for cash exercise of warrants, net (in dollars per share)			$ 3.59
Stock issued for cash, net (in dollars per share)			$ 4.04
Minimum [Member]
Stock issued for cash, net (in dollars per share)	$ 4.00	$ 3.00
Maximum [Member]
Stock issued for cash, net (in dollars per share)	$ 5.69	$ 5.05

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2017
Employee Benefit Plan [Abstract]
Employee Benefit Plan	Note 10 − Employee Benefit Plan We sponsor a defined contribution 401k plan covering substantially all our employees. Our matching contribution to the plan was approximately $84, $90 and $59 in 2017, 2016 and 2015, respectively.

Employee Benefit Plan (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefit Plan [Abstract]
Matching contribution to defined contribution plan	$ 84	$ 90	$ 59

Income Taxes, Net Operating Losses (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Pre-tax losses available for carry forward	$ 17	$ 28	$ 29