Annual report pursuant to Section 13 and 15(d)

Cover Page

v3.19.3.a.u2
Cover Page - USD ($)
$ in Billions
 12 Months Ended
Dec. 31, 2019
Feb. 25, 2020
Jun. 30, 2019
Entity Information [Line Items]      
Document Type 10-K    
Document Period End Date Dec. 31, 2019    
Document Annual Report true    
Document Transition Report false    
Entity File Number 001-37351    
Entity Registrant Name National Storage Affiliates Trust    
Entity Central Index Key 0001618563    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Incorporation, State or Country Code MD    
Entity Tax Identification Number 46-5053858    
Entity Address, Address Line One 8400 East Prentice Avenue, 9th Floor    
Entity Address, City or Town Greenwood Village    
Entity Address, State or Province CO    
Entity Address, Postal Zip Code 80111    
City Area Code 720    
Local Phone Number 630-2600    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 1.7
Entity Common Stock, Shares Outstanding   59,683,668  
Documents Incorporated by Reference Portions of the registrant's definitive proxy statement for its annual meeting of shareholders are incorporated by reference into Part III of this Annual Report on Form 10-K.    
Common Shares of Beneficial Interest, $0.01 par value per share      
Entity Information [Line Items]      
Title of 12(b) Security Common Shares of Beneficial Interest, $0.01 par value per share    
Trading Symbol NSA    
Security Exchange Name NYSE    
Series A Cumulative Redeemable Preferred Shares of Beneficial Interest, par value $0.01 per share      
Entity Information [Line Items]      
Title of 12(b) Security Series A Cumulative Redeemable Preferred Shares of Beneficial Interest, par value $0.01 per share    
Trading Symbol NSA Pr A    
Security Exchange Name NYSE