Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company and Nature of Operations	The Company and Nature of Operations FalconStor Software, Inc., a Delaware Corporation (the "Company"), is a leading software-defined storage company offering a converged data services software platform that is hardware agnostic. The Company develops, manufactures and sells data migration, business continuity, disaster recovery, optimized backup and de-duplication solutions and provides the related maintenance, implementation and engineering services.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management 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 reporting period. The Company’s significant estimates include those related to revenue recognition, accounts receivable allowances, share-based payment compensation, valuation of derivatives, capitalizable software development costs, valuation of goodwill and other intangible assets and income taxes. Actual results could differ from those estimates. The financial market volatility in many countries where the Company operates has impacted and may continue to impact the Company’s business. Such conditions could have a material impact to the Company’s significant accounting estimates discussed above.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America have been condensed or omitted pursuant to such rules and regulations relating to interim financial statements. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly the financial position of the Company at September 30, 2015, and the results of its operations for the three and nine months ended September 30, 2015 and 2014. The results of operations of any interim period are not necessarily indicative of the results of operations to be expected for the full fiscal year. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes set forth in the Company's Annual Report on Form 10-K for the year ended December 31, 2014 ("2014 Form 10-K").
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2014, the Financial Accounting Standards Board (the "FASB") issued new guidance which requires an entity to determine whether the host contract in a hybrid financial instrument issued in the form of a share is more akin to debt or to equity by considering the economic characteristics and risks of the entire hybrid financial instrument, including the embedded derivative feature that is being evaluated for separate accounting from the host contract. The effects of initially adopting the amendments in this update should be applied on a modified retrospective basis to existing hybrid financial instruments issued in the form of a share as of the beginning of the fiscal year for which the amendments are effective. The new standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015, which for the Company will be the annual period ending December 31, 2016. Early adoption, including adoption in an interim period, is permitted. The Company has not yet adopted this guidance and currently does not expect the adoption of the new guidance by the Company to have a significant impact on our financial results. In August 2014, the FASB issued new guidance which requires an entity to evaluate whether there are conditions or events, in the aggregate, that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the financial statements are available to be issued when applicable), and to provide related footnote disclosures in certain circumstances. The new standard is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter, which for the Company will be the annual period ending December 31, 2016. Early application is permitted. The Company has not yet adopted this guidance and currently does not expect the adoption of the new guidance by the Company to have a significant impact on our financial reporting or disclosures. In May 2014, the FASB issued new guidance which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. This new guidance will replace most existing revenue recognition guidance in Generally Accepted Accounting Principles in the United States when it becomes effective. The new standard is effective for the annual period ending after December 15, 2017, including interim reporting period within that period, which for the Company will be the annual period ending December 31, 2018. Early application as of January 1, 2017 is permitted. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that this new guidance will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its financial reporting.
Revenue Recognition	Revenue Recognition The Company derives its revenue from sales of its products, support and services. Product revenue consists of the Company’s software integrated with industry standard hardware and sold as complete turn-key integrated solutions, as stand-alone software applications or sold on a subscription or consumption basis. Depending on the nature of the arrangement revenue related to turn-key solutions and stand-alone software applications are generally recognized upon shipment and delivery of license keys. For certain arrangements revenue is recognized based on usage or ratably over the term of the arrangement. Support and services revenue consists of both maintenance revenues and professional services revenues. Revenue is recorded net of applicable sales taxes. In accordance with the authoritative guidance issued by the FASB on revenue recognition, the Company recognizes revenue when persuasive evidence of an arrangement exists, the fee is fixed or determinable, delivery has occurred, and collection of the resulting receivable is deemed probable. Products delivered to a customer on a trial basis are not recognized as revenue until the trial period has ended and acceptance has occurred by the customer. Reseller and distributor customers typically send the Company a purchase order when they have an end user identified. For bundled arrangements that include either maintenance or both maintenance and professional services, the Company uses the residual method to determine the amount of product revenue to be recognized. Under the residual method, consideration is allocated to the undelivered elements based upon vendor-specific objective evidence (“VSOE”) of the fair value of those elements, with the residual of the arrangement fee allocated to and recognized as product revenue. If VSOE does not exist for all undelivered elements of an arrangement, the Company recognizes total revenue from the arrangement ratably over the term of the maintenance agreement. The Company's long-term portion of deferred revenue consists of (i) payments received for maintenance contracts with terms in excess of one year as of the balance sheet date, and (ii) payments received for product sales bundled with multiple years of maintenance but for which VSOE did not exist for all undelivered elements of the arrangement. The Company provides an allowance for product returns as a reduction of revenue, based upon historical experience and known or expected trends. When more than one element, such as hardware, software and services are contained in a single arrangement, the Company will first allocate revenue based upon the relative selling price into two categories: (1) non-software components, such as hardware and any hardware-related items, as required system software that functions with the hardware to deliver the essential functionality of the hardware and related post-contract customer support, and software as service subscriptions and (2) software components and applications, such as post-contract customer support and other services. The Company will then allocate revenue within the non-software category to each element based upon their relative selling price using a hierarchy of VSOE, third-party evidence of selling price (“TPE”) or estimated selling prices (“ESP”), if VSOE or TPE does not exist. The Company will allocate revenue within the software category to the undelivered elements based upon their fair value using VSOE with the residual revenue allocated to the delivered elements. If the Company cannot objectively determine the VSOE of the fair value of any undelivered software element, the Company will defer revenue for all software components until all elements are delivered and services have been performed, until fair value can objectively be determined for any remaining undelivered elements, or until software maintenance is the only undelivered element which the Company has VSOE for, in which case revenue is recognized over the maintenance term for all software elements. Revenues associated with maintenance services are deferred and recognized as revenue ratably over the term of the contract. Revenues associated with software implementation and software engineering services are recognized when the services are performed. Costs of providing these services are included in cost of support and services. The Company has entered into various distribution, licensing and joint promotion agreements with OEMs, whereby the Company has provided to the OEM a non-exclusive software license to install the Company’s software on certain hardware or to resell the Company’s software in exchange for payments based on the products distributed by these OEMs. Such payments from the OEM or distributor are recognized as revenue in the period reported by the OEM. From time to time the Company will enter into funded software development arrangements. Under such arrangements, revenue recognition will not commence until final delivery and/or acceptance of the product. For arrangements where the Company has VSOE for the undelivered elements, the Company will follow the residual method and recognize product revenue upon final delivery and/or acceptance of the product. For arrangements where the Company does not have VSOE for the undelivered elements, the Company will recognize the entire arrangement fee ratably commencing at the time of final delivery and/or acceptance through the end of the service period in the arrangement. Certain arrangements, for which VSOE of fair value for the undelivered maintenance elements cannot be established, are accounted for as a single unit of account. The revenue recognized from single units of accounting are typically allocated and classified on the consolidated statements of operations as product revenue and support and services revenue. Since VSOE cannot be established, VSOE of similar maintenance offerings provides the basis for the support and services revenue classification, and the remaining residual consideration provides the basis for the product revenue classification. In 2013, the Company entered into a joint development agreement whereby final acceptance of the software delivered under the joint development agreement occurred on November 16, 2014. During 2014, the Company began to recognize the total committed fee as revenue ratably over a twenty-five and a half month period which began on November 16, 2014 which included a contractual twenty-four month maintenance period. During the first quarter of 2015, the customer elected to terminate its maintenance agreement and as such all unrecognized deferred revenue was accelerated and recognized as product revenue during the quarter. During the nine months ended September 30, 2015, the Company recorded total product revenue of approximately $11.3 million related to this agreement. There was no product revenue recorded during the three months ended September 30, 2015 related to this agreement. As of September 30, 2015, there is no deferred revenue or undelivered services remaining related to this agreement.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.