Quarterly report pursuant to Section 13 or 15(d)

SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS - Narrative (Details)

v3.23.2
SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS - Narrative (Details)
$ / shares in Units, $ in Millions
 3 Months Ended 6 Months Ended
Mar. 16, 2023
USD ($)
property
shares
Mar. 15, 2023
shares
Feb. 27, 2019
USD ($)
$ / shares
Jun. 30, 2023
USD ($)
property
$ / shares
shares
Mar. 31, 2023
shares
Jun. 30, 2022
shares
Mar. 31, 2022
shares
Jun. 30, 2023
USD ($)
property
$ / shares
shares
Dec. 31, 2022
$ / shares
Jul. 11, 2022
USD ($)
May 19, 2021
USD ($)
Class of Stock [Line Items]                      
Common shares of beneficial interest, par value (in dollars per share) | $ / shares     $ 0.01 $ 0.01       $ 0.01 $ 0.01    
Authorized amount | $                   $ 400.0  
Repurchase of common shares (in shares)               1,622,874,000      
Stock repurchased | $               $ 69.3      
Number of self storage properties | property       1,117       1,117      
Common Shares                      
Class of Stock [Line Items]                      
Repurchase of common shares (in shares)         1,622,874            
Redemptions/conversions of units (in shares)       354,936 67,431 294,573 258,477        
Series A Preferred Shares | NSA OP, LP                      
Class of Stock [Line Items]                      
Preferred share/unit dividend rate (percent)   6.00%                  
Series B Preferred Shares                      
Class of Stock [Line Items]                      
Shares tied to promissory note (in shares) 1,059,683                    
Series B Preferred Shares | Personal Mini                      
Class of Stock [Line Items]                      
Series B preferred shares | $ $ 139.6                    
Number of self storage properties | property 15                    
Financing Receivable, after Allowance for Credit Loss | $ $ 26.1                    
Series B preferred shares value | $ 26.1                    
Proceeds from issuance of preferred stock | $ $ 113.3                    
Issuance of shares/units (in shares) 5,668,128                    
Series B Preferred Shares | NSA OP, LP                      
Class of Stock [Line Items]                      
Preferred share/unit dividend rate (percent)   6.00%                  
Preferred shares of beneficial interest, authorized (in shares)   7,000,000                  
Preferred units stated value (in dollars per share) | $ / shares       $ 25.00       $ 25.00      
OP units | NSA OP, LP                      
Class of Stock [Line Items]                      
Unit conversion ratio       1       1      
Issuance of shares/units (in shares)               2,545,063      
OP units | NSA OP, LP | Common Shares                      
Class of Stock [Line Items]                      
Redemptions/conversions of units (in shares)               422,367      
OP units | NSA OP, LP | Northwest Retirement                      
Class of Stock [Line Items]                      
Issuance of shares/units (in shares)               481,811      
OP units | NSA OP, LP | Retirement of Northwest                      
Class of Stock [Line Items]                      
Issuance of shares/units (in shares)               2,545,063      
OP units | DownREIT Partnership                      
Class of Stock [Line Items]                      
Unit conversion ratio       1              
Issuance of shares/units (in shares)               195,573      
Subordinated performance units                      
Class of Stock [Line Items]                      
Time frame prior to conversion for conversion metric (in years)               1 year      
Percentage of cash available for distribution used in conversion ratio calculation               110.00%      
Subordinated performance units | NSA OP, LP                      
Class of Stock [Line Items]                      
Issuance of shares/units, non-voluntary (in shares)               926,623      
Redemptions/conversions of units (in shares)               926,623      
Unit conversion, lock out period (in years)               2 years      
Subordinated performance units | NSA OP, LP | Northwest Retirement                      
Class of Stock [Line Items]                      
Redemptions/conversions of units (in shares)               397,000      
Subordinated performance units | NSA OP, LP | Retirement of Northwest                      
Class of Stock [Line Items]                      
Issuance of shares/units (in shares)               855,486      
Subordinated performance units | Personal Mini Affiliate | Personal Mini                      
Class of Stock [Line Items]                      
Payments to acquire interest in subsidiaries and affiliates | $ $ 26.1                    
LTIP units | NSA OP, LP                      
Class of Stock [Line Items]                      
Unit conversion ratio       1              
Issuance of shares/units (in shares)               214,423      
Conversion of units (in shares)               128,487      
Series A-1 preferred units | NSA OP, LP                      
Class of Stock [Line Items]                      
Preferred share/unit dividend rate (percent)               6.00%      
Unit conversion ratio               1      
Issuance of series A-1 preferred units (in shares)               33,441      
DownREIT Subordinated Performance Performance Units | NSA OP, LP                      
Class of Stock [Line Items]                      
Conversion of stock (in shares)               203,637      
Prior Sales Agreement                      
Class of Stock [Line Items]                      
Value of common and preferred shares authorized under ATM program | $     $ 250.0                
Preferred share/unit dividend rate (percent)     6.00%                
At The Market Program                      
Class of Stock [Line Items]                      
Value of common and preferred shares authorized under ATM program | $                     $ 400.0
Value of remaining available offered shares | $       $ 169.1       $ 169.1     $ 31.0
Series A preferred shares | NSA OP, LP                      
Class of Stock [Line Items]                      
Preferred units cash redemption price (in dollars per share) | $ / shares       $ 25.00       $ 25.00