Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 19, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	SELF
Entity Registrant Name	GLOBAL SELF STORAGE, INC.
Entity Central Index Key	0001031235
Current Fiscal Year End Date	--12-31
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		9,419,393
Entity Shell Company	false
Entity File Number	001-12681
Entity Tax Identification Number	13-3926714
Entity Address, Address Line One	11 Hanover Square
Entity Address, Address Line Two	12th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10005
City Area Code	212
Local Phone Number	785-0900
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	MD
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common shares, $0.01 par value per share
Security Exchange Name	NASDAQ