Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 09, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
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	001-39608
Entity Registrant Name	INTRUSION INC.
Entity Central Index Key	0000736012
Entity Tax Identification Number	75-1911917
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	101 EAST PARK BLVD
Entity Address, Address Line Two	SUITE 1200
Entity Address, City or Town	PLANO
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75074
City Area Code	(972)
Local Phone Number	234-6400
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	INTZ
Security Exchange Name	NASDAQ
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			$ 248,751,286
Entity Common Stock, Shares Outstanding		19,183,776
Auditor Firm ID	726
Auditor Name	Whitley Penn LLP
Auditor Location	Plano, Texas