Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
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, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		44,563,490
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2017