Quarterly report pursuant to Section 13 or 15(d)

EARNINGS PER SHARE - Narrative (Details)

v3.22.1
EARNINGS PER SHARE - Narrative (Details)
3 Months Ended
Mar. 31, 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
Minimum conversion period (in years) 1 year
NSA OP, LP | LTIP 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
Minimum conversion period (in years) 5 years
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) 5 years
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) 413,111
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) 252,894
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) 58,300,000