Cover Page - shares	3 Months Ended
	Mar. 31, 2021	May 14, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	0-18649
Entity Registrant Name	National Security Group, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	63-1020300
Entity Address, Address Line One	661 East Davis Street
Entity Address, City or Town	Elba,
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	36323
City Area Code	334
Local Phone Number	897-2273
Title of 12(b) Security	Common Stock, par value $1.00 per share
Trading Symbol	NSEC
Security Exchange Name	NASDAQ
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 Common Stock, Shares Outstanding		2,530,370
Entity Central Index Key	0000865058
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false