Quarterly report pursuant to Section 13 or 15(d)

EARNINGS PER SHARE - Narrative (Details)

v3.23.3
EARNINGS PER SHARE - Narrative (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2023
shares
Sep. 30, 2022
shares
Sep. 30, 2023
Sep. 30, 2022
shares
NSA OP, LP And DownREIT Partnership | Subordinated performance units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Unit conversion ratio 1      
Minimum conversion period (in years) 2 years      
NSA OP, LP | OP units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Unit conversion ratio 1   1  
NSA OP, LP | LTIP units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Unit conversion ratio 1   1  
NSA OP, LP | Subordinated performance units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Unit conversion ratio     1  
DownREIT Partnership | OP units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Unit conversion ratio 1      
LTIP units with vesting based on service or market condition        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Equity interests excluded from computation of diluted earnings per share (in shares) 501,311      
LTIP units with vesting based on future acquisitions        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Equity interests excluded from computation of diluted earnings per share (in shares) 216,000      
OP units, DownREIT OP units, Subordinated performance units, DownREIT subordinated performance units        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Equity interests excluded from computation of diluted earnings per share (in shares)   58,600,000   58,500,000