Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 24, 2021	Jun. 30, 2020
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Filer Category	Non-accelerated Filer
Entity Registrant Name	ELECTRO SENSORS INC
Entity Central Index Key	0000351789
Current Fiscal Year End Date	--12-31
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding		3,395,521
Entity Public Float			$ 7,800,000
Trading Symbol	ELSE
Entity Emerging Growth Company	false
Entity Small Business	true
Document Annual Report	true
Document Transition Report	false
Entity File Number	000-09587
Entity Incorporation, State or Country Code	MN
Entity Tax Identification Number	41-0943459
Entity Address, Address Line One	6111 Blue Circle Drive
Entity Address, City or Town	Minnetonka
Entity Address, State or Province	MN
City Area Code	952
Local Phone Number	930-0100
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Address, Postal Zip Code	55343-9108