Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document And Entity Information
Entity Registrant Name	FALCONSTOR SOFTWARE INC
Entity Central Index Key	0000922521
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		97,934,091
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2018