| Document and Entity Information Document | Nov. 09, 2023 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 09, 2023 |
| Entity Registrant Name | National Storage Affiliates Trust |
| Entity Central Index Key | 0001618563 |
| Amendment Flag | false |
| Current Fiscal Year End Date | --12-31 |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-37351 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| 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 |
| Series B Cumulative Redeemable Preferred Shares of Beneficial Interest, par value $0.01 per share | |
| Entity Information [Line Items] | |
| Title of 12(b) Security | Series B Cumulative Redeemable Preferred Shares of Beneficial Interest, par value $0.01 per share |
| Trading Symbol | NSA Pr B |
| Security Exchange Name | NYSE |
