Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2017
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 storage software 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.
Substantial Doubt about Going Concern [Text Block]	Going Concern A fundamental principle of the preparation of financial statements in accordance with accounting principles generally accepted in the United States of America ("GAAP") is the assumption that an entity will continue in existence as a going concern, which contemplates continuity of operations and the realization of assets and settlement of liabilities occurring in the ordinary course of business. This principle is applicable to all entities except for entities in liquidation or entities for which liquidation appears imminent. In accordance with this requirement, the Company has prepared its consolidated financial statements on a going concern basis. The Company has incurred significant operating losses in the previous eight years and negative cash flow from operations in five of the previous eight years. The Company currently has a working capital deficiency of $12.6 million, which is inclusive of current deferred revenue of $12.3 million and a stockholders' deficit of $22.5 million. During the nine months ended September 30, 2017, the Company incurred a net loss of $0.3 million and cash flow used in operations of $1.6 million. The Company's total cash balance at September 30, 2017 was $1.8 million, a decrease of $1.6 million as compared to December 31, 2016. In addition to these financial metrics, as of December 31, 2016, the Company was not in compliance with the financial covenants of the Series A redeemable convertible preferred stock, which were mutually agreed to annually, for two consecutive quarters. This breach provides the holder of the Series A redeemable convertible preferred stock with the right to require the Company to redeem any of the Series A redeemable convertible preferred stock at the greater of 100% of the stated value plus accrued and unpaid dividends or the product of the number of shares of common stock underlying the Series A redeemable convertible preferred stock and the closing price of the Company's common stock as of December 31, 2016. To date, the holder of the Series A redeemable convertible preferred stock has neither exercised nor waived this right and accordingly this right may be exercised at any time. In addition, as of August 5, 2017, the holder of the Series A redeemable convertible preferred stock has the right to request a redemption of the Series A redeemable convertible preferred stock. If the holders request that the Series A redeemable convertible preferred stock be redeemed, the Company may not have sufficient liquidity or sufficient surplus as such term is defined under the Delaware General Business Corporation Law ("DGCL") to undertake the redemption. If the Company does not redeem the Series A redeemable convertible preferred stock, the holder of the Series A redeemable convertible preferred stock can pursue other remedies. Refer to Note (11) Series A Redeemable Convertible Preferred Stock for further discussion regarding these other remedies. As further described below, the Company's reduced cash balance and history of losses both in and of itself, and in combination with the redemption rights of the holders of the Series A redeemable convertible preferred stock, raise substantial doubt about the Company's ability to continue as a going concern within one year after November 20, 2017 (the date that these financial statements were issued). The Company's ability to continue as a going concern, including in the event of a redemption request by the holder, depends on its ability to execute its business plan, increase revenue and billings and reduce expenditures. During 2016, the Company continued to focus on aligning its expense structure with revenue expectations which included tighter expense controls and overall operational efficiencies which better align the Company's current business plan on a run-rate basis. These efficiencies include among other items, stream-lined personnel related costs and global overhead costs and efficiencies realized on the Company's redesigned go-to-market coverage models. In June 2017, the Company's Board of Directors, approved a comprehensive plan to increase operating performance (the “2017 Plan”). The 2017 Plan will result in a realignment and reduction in workforce. The 2017 Plan was substantially completed as of June 30, 2017. These actions are anticipated to result in an annualized cost savings of approximately $10.0 million. In connection with the 2017 Plan, the Company incurred severance expense of $1.0 million. In making these changes, the Company prioritized customer support and development while consolidating operations and cutting direct sales resources, therefore allowing the Company to focus on its install base and develop more efficient market channels. The Company's worldwide headcount was 83 employees as of September 30, 2017, compared with 166 and 226 employees as of December 31, 2016 and 2015, respectively. Although, the Company was able to reduce its operating expenses from the previous year, the Company's bookings, billings and revenue continued to decline which negatively impacts the Company's ability to continue as a going concern. As previously disclosed in the Company’s public filings, the Company’s failure to generate sufficient revenue, billing control or further reduce expenditures and/or the inability to obtain financing will result in an inability of the Company to continue as a going concern. While the Company was able to reduce expenditures and hence generated net income for the three months ended September 30, 2017 and the Company’s cash and cash equivalents increased slightly between June 30, 2017 and September 30, 2017, the Company’s revenues continued to decrease for such period both in comparison to the comparable period in the fiscal year ended December 31, 2016 as well as compared to the three months ended June 30, 2017. In addition, subsequent to September 30, 2017, the Company’s cash and cash equivalents has significantly decreased. Accordingly, to ensure that the Company could meet its operating cash flow needs and continue as a going concern, the Company entered into a short term secured loan in the principal amount of $500,000 (the “Short-Term Loan”) with HCP-FVA, LLC, an affiliate of Hale Capital Partners, LP (together “Hale Capital”) and secured a commitment (the “Commitment”) from Hale Capital to purchase up to $3 million of units from the Company (inclusive of units issued in satisfaction of the Company’s obligations under the Short-Term Loan). The Company has received the Short-Term Loan. The Company’s ability to continue as a going concern will depend on whether it receives the balance of the funds from the Commitment as well as its ability to increase revenues and/or further reduce expenditures of which there can be no assurance. The issuance of warrants in connection with the Short Term Loan and Commitment will have a substantial dilutive effect on all existing stockholders. Please see “Note 17 - Subsequent Event” and “Item 5. - Other Information” for more information on the Short-Term Loan and the Commitment. To the extent the Company incurs losses and or is unable to receive the balance of the funds from the Commitment, the Company will need to seek additional financing to continue as a going concern and there can be no assurance that the Company will be able to obtain financing or that such financing will be on favorable terms. Similar to the Short Term Loan and the Commitment any such financing could be dilutive to our shareholders. Failure to generate sufficient revenue, billings, control or further reduce expenditures and/or the inability to obtain financing will result in an inability of the Company to continue as a going concern.
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 GAAP 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 on 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 GAAP 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, 2017, and the results of its operations for the three and nine months ended September 30, 2017 and 2016. 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, 2016 ("2016 Form 10-K").
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board ("FASB") issued new guidance on accounting for employee share-based payment awards to simplify the accounting related to several aspects of accounting for share-based payment transactions, including income tax consequences of share-based payment transactions, classification of awards as either equity or liabilities, forfeitures, and classification on the statement of cash flows. The Company adopted this guidance as of January 1, 2017. In accordance with this new guidance the Company has made an entity-wide accounting policy election to account for forfeitures when they occur. As a result of this election, the Company recognized additional stock-based compensation expense of approximately $0.1 million in the first quarter of 2017 to adjust for actual forfeitures on historical share-based payment awards. In January 2017, the FASB issued new guidance on accounting for goodwill to simplify the goodwill impairment test by eliminating Step 2 of the goodwill impairment test. This new guidance also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. The new standard is effective for the annual period beginning after December 15, 2019, including interim reporting periods within that period, which for the Company is the annual period ending December 31, 2020. Early adoption is permitted. The Company elected to adopt this guidance as of January 1, 2017, prospectively for impairment tests performed subsequent to January 1, 2017. The Company's single reporting unit for purposes of its goodwill impairment test had a negative carrying value and thus the Company determined there was no impairment of goodwill. During 2017 there have been no triggering events that would require a goodwill impairment test to be performed prior to the Company's annual goodwill impairment test. The adoption of this guidance did not have an impact on the Company's financial statements and related disclosures. (g) Recently Issued Accounting Pronouncements In May 2017, the FASB issued new guidance on stock-based compensation to provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the stock-based compensation guidance to a change to the terms or conditions of a share-based payment award. The amendments in this update provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. This new guidance requires application on a prospective basis. This update is effective for public entities for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, with early adoption permitted, which for the Company will be the annual period ending December 31, 2018. 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 the Company's financial statements and related disclosures. In March 2017, the FASB issued new guidance on retirement benefits, which requires employers to disaggregate the service cost component from other components of net periodic benefit costs and to disclose the amounts of net periodic benefit costs that are included in each income statement line item. The standard requires employers to report the service cost component in the same line item as other compensation costs and to report the other components of net periodic benefit costs (which include interest costs, expected return on plan assets, amortization of prior service cost or credits and actuarial gains and losses) separately and outside a subtotal of operating income. The income statement guidance requires application on a retrospective basis. This update is effective for public entities for annual periods beginning after December 15, 2017, including interim periods, with early adoption permitted, which for the Company will be the annual period ending December 31, 2018. 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 the Company's financial statements and related disclosures. In August 2016, the FASB issued new guidance on presentation and classification of eight specific items within the statement of cash flows, including (i) debt prepayment or debt extinguishment costs, (ii) settlement of zero-coupon debt instruments or other debt instruments with coupon rates that are insignificant in relation to the effective interest rate of the borrowing, (iii) contingent consideration payments made after a business combination, (iv) proceeds from the settlement of insurance claims, (v) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies, (vi) distributions received from equity method investees, (vii) beneficial interests in securitization transactions, and (viii) separately identifiable cash flows and application of the predominance principle. This update is effective for annual reporting periods, and interim periods therein, beginning after December 15, 2017, which for the Company will be the annual period ending December 31, 2018. 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 to have a significant impact on the Company's financial statements and related disclosures. In February 2016, the FASB issued new guidance on leases to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This new guidance will replace existing guidance on leases in accounting principles generally accepted in the United States when it becomes effective. The new standard is effective for the annual period beginning after December 15, 2018, including interim reporting periods within that period, which for the Company will be the annual period ending December 31, 2019. Early application is permitted. The standard requires the use of a modified retrospective transition method; however, certain optional practical expedients may be applied. The Company's preliminary analysis indicates that the Company will recognize a liability for remaining lease payments and a right-of-use asset related to the Company's operating lease covering its corporate office facility that expires in April 2021. Currently the Company's additional operating leases related to offices in foreign countries are set to expire prior to adoption of the new guidance. The Company is in the initial stages of evaluating the effect of the standard on the Company's financial statements. In January 2016, the FASB issued new guidance on the recognition, measurement, presentation and disclosure of financial assets and financial liabilities. The standard (i) requires an entity to measure equity investments, except those accounted for under the equity method of accounting or those that result in consolidation of the investee, at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring an entity to perform a qualitative assessment to identify impairment, (iii) changes certain presentation and disclosure requirements related to financial assets and financial liabilities, and (iv) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. The amendments in this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, which for the Company will be the annual period ending December 31, 2018. Early adoption, including adoption in an interim period, is not permitted except for certain amendments in this update. 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 the Company's financial statements and related 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 GAAP in the United States when it becomes effective. The new standard is effective for the annual period beginning after December 15, 2017, including interim reporting periods within that period, which for the Company will be the annual period ending December 31, 2018. 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 formed an implementation team to evaluate the standard's effect on the Company's financial statements. The Company has historically deferred revenue for certain deliverables in its multiple-element arrangements due to a lack of vendor-specific objective evidence (“VSOE”) for purposes of the allocation of the transaction consideration. The Company performed a preliminary analysis, which indicated that the Company will recognize revenue for these arrangements earlier under the new standard than under the existing guidance due to the elimination of the VSOE requirement. The Company has not yet determined what other impact may result from application of the new standard. The Company will use the cumulative effect transition method upon adoption of this guidance. The Company has not progressed beyond the initial stages of evaluating the effect of the standard on the Company's financial statements and currently has concerns about its ability to timely adopt this standard due to its current status and resources.
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 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 does not have 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 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.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Share-Based Payments The Company accounts for share-based payments in accordance with the authoritative guidance issued by the FASB on share-based compensation, which establishes the accounting for transactions in which an entity exchanges its equity instruments for goods or services. Under the provisions of the authoritative guidance, share-based compensation expense is measured at the grant date, based on the fair value of the award, and is recognized as an expense over the requisite employee service period (generally the vesting period), net of actual forfeitures. For share-based payment awards that contain performance criteria share-based compensation, expense is recorded when the achievement of the performance condition is considered probable of achievement and is recorded on a straight-line basis over the requisite service period. If such performance criteria are not met, no compensation cost is recognized and any recognized compensation cost is reversed. The Company estimates the fair value of share-based payments using the Black-Scholes option-pricing model or the Monte Carlo simulation model if a market condition exists. Share-based compensation expense for a share-based payment award with a market condition is recorded on a straight-line basis over the longer of the explicit service period or the service period derived from the Monte Carlo simulation. Additionally, share-based awards to non-employees are expensed over the period in which the related services are rendered at their fair value. All share-based awards are expected to be fulfilled with new shares of common stock.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill and Other Intangible Assets Goodwill represents the excess of the purchase price over the estimated fair value of net tangible and identifiable intangible assets acquired in business combinations. The Company has not amortized goodwill related to its acquisitions, but instead tests the balance for impairment. The Company evaluates goodwill for impairment annually or more frequently when an event occurs or circumstances change that indicate that the carrying value may not be recoverable. The Company tests goodwill for impairment by comparing the book value of net assets to the fair value of the reporting unit. If the fair value is determined to be less than the book value, the computed difference represents the amount of impairment. The Company's single reporting unit for purposes of its goodwill impairment test has a negative carrying value and thus the Company has determined there was no impairment of goodwill. During the second and third quarters of 2017, there were no triggering events that would require a goodwill impairment test to be performed prior to the Company's annual goodwill impairment test.