Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 31, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K/A
Amendment Flag	true
Amendment Description	This Amendment No. 1 on Form 10-K/A (this "Amendment") supplements the Original Filing by amending and restating Part III, Items 10 through 14 of the Original Filing.
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	0-23970
Entity Registrant Name	FALCONSTOR SOFTWARE, INC.
Entity Central Index Key	0000922521
Entity Tax Identification Number	77-0216135
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	701 Brazos Street
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Austin
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78701
City Area Code	631
Local Phone Number	777-5188
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 12,745,946
Entity Common Stock, Shares Outstanding		7,082,276
Auditor Name	MARCUM LLP
Auditor Location	Costa Mesa, CA
Auditor Firm ID	688