Significant Contract, License and Royalty Agreements	12 Months Ended
Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Significant Contract, License and Royalty Agreements	6. Significant Contract, License and Royalty Agreements Contracts IPPOX In April 2015, the Company entered into a $4.1 million contract with the IPPOX Foundation to manufacture HIV-antigen plasmid DNA as a component of vaccine regimens to be evaluated in clinical trials for the prevention of HIV infection. IPPOX is a Swiss non-profit foundation that participates in the conduct of HIV vaccine clinical trials under the auspices of the Pox-Protein Public-Private Partnership, or P5, funded by the Bill & Melinda Gates Foundation and the U.S. National Institute of Allergy and Infectious Diseases, or NIAID. These plasmids were shipped and the related revenue of $4.1 million was recognized in December 2015. This contract builds upon the Company’s 2010 agreement with IPPOX to manufacture plasmid DNA for HIV vaccine clinical trials. Astellas In July 2011, the Company entered into license agreements with Astellas Pharma Inc., or Astellas, granting Astellas exclusive, worldwide, royalty-bearing licenses under certain of the Company’s know-how and intellectual property to develop and commercialize certain products containing plasmids encoding certain forms of glycoprotein B and/or phosphoprotein 65, including ASP0113 but excluding CyMVectin™. Under the agreements, Astellas is responsible for the worldwide development and commercialization of products in the licensed field, at its expense, and has agreed to use commercially reasonable efforts to develop, obtain regulatory approval for and commercialize at least one licensed product for use in certain immunocompromised patients in the licensed field in the United States and certain other major markets. Under the terms of the license agreements, Astellas paid a nonrefundable upfront license fee of $25.0 million. In 2012, the Company received a $10.0 million milestone payment upon finalization of the trial design for a Phase 3 registration trial of ASP0113 in hematopoietic stem cell transplant recipients. The Company is also entitled to receive additional cash payments potentially totaling $95.0 million for achievement of certain milestones through commercial launch and to receive double-digit royalties on net sales of products. In addition, the Company has an option to co-promote ASP0113 in the United States. Under the terms of a supply and services agreement entered into by the Company and Astellas on the same date, the Company agreed to perform certain development and regulatory activities, at Astellas’ expense, and to supply licensed products to Astellas, at Astellas’ expense, for use in development and initial commercialization activities in the licensed field. In August 2012, the Company amended its license and supply agreements with Astellas to, among other things, extend the time period that the Company is obligated to supply licensed products for commercial use to Astellas, at Astellas’ expense, modify the allocation of $95.0 million of milestone payments among certain milestones through commercial launch and modify the structure of the royalties on net sales from a fixed double digit royalty to tiered double digit royalties. The Company identified the deliverables at the inception of the agreements. The Company has determined that the license and related know-how, the development and regulatory services and the drug product supply individually represent separate units of accounting, because each deliverable has standalone value. The best estimated selling prices for these units of accounting was determined based on market conditions, the terms of comparable collaborative arrangements for similar technology in the pharmaceutical and biotechnology industry and entity-specific factors, such as the terms of the Company’s previous collaborative agreements, the Company’s pricing practices and pricing objectives and the nature of the research and development services to be performed for the partner. The arrangement consideration was allocated to the deliverables based on the relative selling price method. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable; therefore, the amount allocated to the licenses was limited to the extent of cash received. As a result, during the years ended December 31, 2015, 2014 and 2013, the Company recognized $1.8 million, $1.6 million and $0.7 million, respectively, related to the license fee and know-how. The Company will recognize the amounts allocated to research and development services as revenues under the agreements as the related services are delivered and as reimbursements are received. During the years ended December 31, 2015, 2014 and 2013, the Company recognized $8.7 million, $7.8 million and $4.4 million, respectively, of revenue related to contract services delivered. The Company will recognize as revenue the amounts allocated to the sales of drug product when the sale of that drug product has met all required specifications and the related title and risk of loss and damages have passed to Astellas. During the years ended December 31, 2015, 2014 and 2013, the Company recognized $6.0 million, $5.5 million and $1.2 million, respectively, of revenue related to drug product delivered. The Company is eligible to receive additional cash payments upon the achievement of specified regulatory and commercial milestones. The Company has determined that each of the regulatory and commercial milestones meets the definition of a milestone and that each milestone is substantive in accordance with the milestone method of revenue recognition. Accordingly, the Company expects to recognize such regulatory and commercial milestone payments as revenues under the agreements upon achievement of each milestone. In-licensing Agreements Astellas In March 2015, the Company entered into a license agreement with Astellas which grants to the Company exclusive worldwide license to develop and commercialize a novel antifungal, VL-2397. As consideration for the rights under the license, the Company issued 861,216 shares of our common stock to Astellas and made an up-front payment of $250,000 in cash. The License Agreement provides for potential development, regulatory and sales milestone payments totaling up to $99.0 million, the vast majority of which are payable upon achievement of commercial and sales milestones, and single-digit royalties on net sales of commercial products. The Company is responsible for the worldwide development, manufacturing and commercialization of licensed products, at the Company’s cost, and we are required to use commercially reasonable efforts with respect to such development and commercialization activities. The license agreement, unless terminated earlier, will continue until expiration of Vical’s royalty obligations with respect to licensed products. Either party may terminate the license agreement earlier if the other party materially breaches the agreement and does not cure the breach within a specified notice period, or upon the other party’s insolvency. Astellas may terminate the license agreement earlier if Vical or any of its affiliates or sublicensees oppose or challenge any of the licensed patents. Vical may terminate the license agreement on a country-by-country basis for reasonable scientific, regulatory, commercial, financial, ethical or other reasons. City of Hope In 2003, the Company licensed from the City of Hope on an exclusive basis various U.S. patents that provide protection for CMV-related polynucleotide based vaccines, including TransVax^TM and CyMVectin^TM vaccine candidates. The agreement expires upon the last to expire of the patent rights licensed by the Company under the agreement, unless earlier terminated as set forth in the agreement. The City of Hope may terminate the agreement early, in accordance with notice provisions set forth in the agreement, if the Company ceases to operate, fails to make payments when due or materially breaches the agreement. Subject to certain conditions, the Company may terminate the agreement early at any time upon prior written notice to the City of Hope. The Company is also obligated to pay a low double-digit percentage of any payments it receives from the sub-license of products that incorporate the licensed technology. The Company paid the City of Hope $0.1 million under the agreement for each of the years ended December 31, 2015, 2014 and 2013. CytRx In 2001, the Company entered into an exclusive agreement with CytRx which grants to the Company the rights to use or sublicense CytRx’s poloxamer technology to enhance viral or non-viral delivery of polynucleotides in all preventive and therapeutic human and animal health applications, including CMV. The agreement excludes applications for four infectious disease vaccine targets that had been licensed to Merck and prostate-specific membrane antigen. In addition, the agreement permits the Company’s use of CytRx’s technology to enhance the delivery of proteins in prime-boost vaccine applications that involve the use of polynucleotides. As part of the agreement, the Company made a $3.8 million up-front payment and agreed to make potential future milestone and royalty payments. The license fee is fully amortized as of December 31, 2013. The Company paid CytRx $0.1 million, $0.1 million and $0.3 million under the agreement for the years ended December 31, 2015, 2014 and 2013, respectively. Milestone Payments The Company may be required to make future payments to its licensors based on the achievement of milestones set forth in various in-licensing agreements. In most cases, these milestone payments are based on the achievement of development or regulatory milestones, including the exercise of options to obtain licenses related to specific disease targets, commencement of various phases of clinical trials, filing of product license applications, approval of product licenses from the FDA or a foreign regulatory agency, and the first commercial sale of a related product. Payment for the achievement of milestones under the Company’s in-license agreements is highly speculative and subject to a number of contingencies. The aggregate amount of additional milestone payments that the Company could be required to pay under its active in-license agreements in place at December 31, 2015, is approximately $106.1 million. These amounts assume that all remaining milestones associated with the milestone payments are met. In the event that product license approval for any of the related products is obtained, the Company may be required to make royalty payments in addition to these milestone payments. Although the Company believes that some of the milestones contained in its in-license agreements may be achieved, it is highly unlikely that a significant number of them will be achieved. Because the milestones are contingent the Company is not in a position to reasonably estimate how much, if any, of the potential milestone payments will ultimately be paid. Additionally, under the in-license agreements, many of the milestone events are related to progress in clinical trials which the Company estimates will take several years to achieve.

6. Significant Contract, License and Royalty Agreements

Contracts

IPPOX

In April 2015, the Company entered into a $4.1 million contract with the IPPOX Foundation to manufacture HIV-antigen plasmid DNA as a component of vaccine regimens to be evaluated in clinical trials for the prevention of HIV infection. IPPOX is a Swiss non-profit foundation that participates in the conduct of HIV vaccine clinical trials under the auspices of the Pox-Protein Public-Private Partnership, or P5, funded by the Bill & Melinda Gates Foundation and the U.S. National Institute of Allergy and Infectious Diseases, or NIAID. These plasmids were shipped and the related revenue of $4.1 million was recognized in December 2015. This contract builds upon the Company’s 2010 agreement with IPPOX to manufacture plasmid DNA for HIV vaccine clinical trials.

Astellas

In July 2011, the Company entered into license agreements with Astellas Pharma Inc., or Astellas, granting Astellas exclusive, worldwide, royalty-bearing licenses under certain of the Company’s know-how and intellectual property to develop and commercialize certain products containing plasmids encoding certain forms of glycoprotein B and/or phosphoprotein 65, including ASP0113 but excluding CyMVectin™. Under the agreements, Astellas is responsible for the worldwide development and commercialization of products in the licensed field, at its expense, and has agreed to use commercially reasonable efforts to develop, obtain regulatory approval for and commercialize at least one licensed product for use in certain immunocompromised patients in the licensed field in the United States and certain other major markets. Under the terms of the license agreements, Astellas paid a nonrefundable upfront license fee of $25.0 million.

In 2012, the Company received a $10.0 million milestone payment upon finalization of the trial design for a Phase 3 registration trial of ASP0113 in hematopoietic stem cell transplant recipients. The Company is also entitled to receive additional cash payments potentially totaling $95.0 million for achievement of certain milestones through commercial launch and to receive double-digit royalties on net sales of products. In addition, the Company has an option to co-promote ASP0113 in the United States. Under the terms of a supply and services agreement entered into by the Company and Astellas on the same date, the Company agreed to perform certain development and regulatory activities, at Astellas’ expense, and to supply licensed products to Astellas, at Astellas’ expense, for use in development and initial commercialization activities in the licensed field.

In August 2012, the Company amended its license and supply agreements with Astellas to, among other things, extend the time period that the Company is obligated to supply licensed products for commercial use to Astellas, at Astellas’ expense, modify the allocation of $95.0 million of milestone payments among certain milestones through commercial launch and modify the structure of the royalties on net sales from a fixed double digit royalty to tiered double digit royalties.

The Company identified the deliverables at the inception of the agreements. The Company has determined that the license and related know-how, the development and regulatory services and the drug product supply individually represent separate units of accounting, because each deliverable has standalone value. The best estimated selling prices for these units of accounting was determined based on market conditions, the terms of comparable collaborative arrangements for similar technology in the pharmaceutical and biotechnology industry and entity-specific factors, such as the terms of the Company’s previous collaborative agreements, the Company’s pricing practices and pricing objectives and the nature of the research and development services to be performed for the partner. The arrangement consideration was allocated to the deliverables based on the relative selling price method.

The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable; therefore, the amount allocated to the licenses was limited to the extent of cash received. As a result, during the years ended December 31, 2015, 2014 and 2013, the Company recognized $1.8 million, $1.6 million and $0.7 million, respectively, related to the license fee and know-how. The Company will recognize the amounts allocated to research and development services as revenues under the agreements as the related services are delivered and as reimbursements are received. During the years ended December 31, 2015, 2014 and 2013, the Company recognized $8.7 million, $7.8 million and $4.4 million, respectively, of revenue related to contract services delivered. The Company will recognize as revenue the amounts allocated to the sales of drug product when the sale of that drug product has met all required specifications and the related title and risk of loss and damages have passed to Astellas. During the years ended December 31, 2015, 2014 and 2013, the Company recognized $6.0 million, $5.5 million and $1.2 million, respectively, of revenue related to drug product delivered. The Company is eligible to receive additional cash payments upon the achievement of specified regulatory and commercial milestones. The Company has determined that each of the regulatory and commercial milestones meets the definition of a milestone and that each milestone is substantive in accordance with the milestone method of revenue recognition. Accordingly, the Company expects to recognize such regulatory and commercial milestone payments as revenues under the agreements upon achievement of each milestone.

In-licensing Agreements

Astellas

In March 2015, the Company entered into a license agreement with Astellas which grants to the Company exclusive worldwide license to develop and commercialize a novel antifungal, VL-2397. As consideration for the rights under the license, the Company issued 861,216 shares of our common stock to Astellas and made an up-front payment of $250,000 in cash. The License Agreement provides for potential development, regulatory and sales milestone payments totaling up to $99.0 million, the vast majority of which are payable upon achievement of commercial and sales milestones, and single-digit royalties on net sales of commercial products. The Company is responsible for the worldwide development, manufacturing and commercialization of licensed products, at the Company’s cost, and we are required to use commercially reasonable efforts with respect to such development and commercialization activities.

The license agreement, unless terminated earlier, will continue until expiration of Vical’s royalty obligations with respect to licensed products. Either party may terminate the license agreement earlier if the other party materially breaches the agreement and does not cure the breach within a specified notice period, or upon the other party’s insolvency. Astellas may terminate the license agreement earlier if Vical or any of its affiliates or sublicensees oppose or challenge any of the licensed patents. Vical may terminate the license agreement on a country-by-country basis for reasonable scientific, regulatory, commercial, financial, ethical or other reasons.

City of Hope

In 2003, the Company licensed from the City of Hope on an exclusive basis various U.S. patents that provide protection for CMV-related polynucleotide based vaccines, including TransVax^TM and CyMVectin^TM vaccine candidates. The agreement expires upon the last to expire of the patent rights licensed by the Company under the agreement, unless earlier terminated as set forth in the agreement. The City of Hope may terminate the agreement early, in accordance with notice provisions set forth in the agreement, if the Company ceases to operate, fails to make payments when due or materially breaches the agreement. Subject to certain conditions, the Company may terminate the agreement early at any time upon prior written notice to the City of Hope. The Company is also obligated to pay a low double-digit percentage of any payments it receives from the sub-license of products that incorporate the licensed technology. The Company paid the City of Hope $0.1 million under the agreement for each of the years ended December 31, 2015, 2014 and 2013.

CytRx

In 2001, the Company entered into an exclusive agreement with CytRx which grants to the Company the rights to use or sublicense CytRx’s poloxamer technology to enhance viral or non-viral delivery of polynucleotides in all preventive and therapeutic human and animal health applications, including CMV. The agreement excludes applications for four infectious disease vaccine targets that had been licensed to Merck and prostate-specific membrane antigen. In addition, the agreement permits the Company’s use of CytRx’s technology to enhance the delivery of proteins in prime-boost vaccine applications that involve the use of polynucleotides. As part of the agreement, the Company made a $3.8 million up-front payment and agreed to make potential future milestone and royalty payments. The license fee is fully amortized as of December 31, 2013. The Company paid CytRx $0.1 million, $0.1 million and $0.3 million under the agreement for the years ended December 31, 2015, 2014 and 2013, respectively.

Milestone Payments

The Company may be required to make future payments to its licensors based on the achievement of milestones set forth in various in-licensing agreements. In most cases, these milestone payments are based on the achievement of development or regulatory milestones, including the exercise of options to obtain licenses related to specific disease targets, commencement of various phases of clinical trials, filing of product license applications, approval of product licenses from the FDA or a foreign regulatory agency, and the first commercial sale of a related product. Payment for the achievement of milestones under the Company’s in-license agreements is highly speculative and subject to a number of contingencies.

The aggregate amount of additional milestone payments that the Company could be required to pay under its active in-license agreements in place at December 31, 2015, is approximately $106.1 million. These amounts assume that all remaining milestones associated with the milestone payments are met. In the event that product license approval for any of the related products is obtained, the Company may be required to make royalty payments in addition to these milestone payments. Although the Company believes that some of the milestones contained in its in-license agreements may be achieved, it is highly unlikely that a significant number of them will be achieved. Because the milestones are contingent the Company is not in a position to reasonably estimate how much, if any, of the potential milestone payments will ultimately be paid. Additionally, under the in-license agreements, many of the milestone events are related to progress in clinical trials which the Company estimates will take several years to achieve.