Commitments and Contingencies (Narrative) (Details)			3 Months Ended	9 Months Ended	12 Months Ended	18 Months Ended
	Apr. 05, 2018 USD ($)	Aug. 14, 2017 USD ($) tranche	Sep. 30, 2018 USD ($) shares	Sep. 30, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2014 position	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Maximum length of warranty on software products				90 days
Upon certain triggering events holders can redeem				100.00%
Restructuring reserve			$ 941,978	$ 941,978	$ 648,399		$ 958,100	$ 461,362
Entity number of employees					81
Lease disposal related costs incurred			1,100,000
Uncertainty in income tax liability			$ 199,169	$ 199,169
Restructuring Costs Under the 2013 Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Number of positions eliminated, worldwide (over 100) | position						100
Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Compensation		$ 350,000
Accrued bonuses		$ 17,500
Percentage of outstanding stock, threshold		15.00%
Severance payment period		6 months
Award requisite period		6 months
Chief Financial Officer [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Compensation	$ 240,000
Accrued bonuses	10,000
Deferred Bonus | Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Accrued bonuses		$ 200,000
Deferred Bonus | Chief Financial Officer [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Accrued bonuses	70,000
Excess Capital	$ 27,500
Upon Stockholder Approval | Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of outstanding stock, threshold		2.50%
Number of tranches | tranche		2
Upon Termination | Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Severance payment period		12 months
Award requisite period		12 months
Change of control period		6 months
FalconStor Software, Inc., 2018 Incentive Stock Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Shares Authorized (in shares) | shares			147,199,698	147,199,698
2017 Plan
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Severance expense					$ 1,200,000
Severance Related Costs
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Restructuring reserve			$ 461,362	$ 461,362	$ 648,399		$ 461,362	$ 461,362