EARNINGS PER SHARE - Narrative (Details)	3 Months Ended
	Mar. 31, 2024 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
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
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)	562,792
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)	208,400