Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document Information [Line Items]
Entity Registrant Name	FALCONSTOR SOFTWARE INC
Entity Central Index Key	0000922521
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 2,768,372
Entity Common Stock, Shares Outstanding		587,255,165
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2018