EARNINGS PER SHARE - Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2024 shares	Sep. 30, 2024 shares
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
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)	540,751	540,751
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	208,400
OP Units, DownREIT OP Units, Vested LTIP 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	58,200,000