EQUITY AND MEZZANINE EQUITY - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) apartmentCommunity shares	Dec. 31, 2022 USD ($) $ / shares shares	Mar. 10, 2022 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Noncontrolling interests , operating partnership, outstanding (in shares) | shares	864,000		864,000		971,000
Noncontrolling interests , operating partnership, issued (in shares) | shares				209,000
Number of apartment communities acquired | apartmentCommunity				3
Preferred shares, shares issued (in shares) | shares	3,881,000		3,881,000		3,881,000
Preferred shares liquidation preference	$ 97,036,000		$ 97,036,000		$ 97,036,000
Common stock outstanding (in shares) | shares	15,052,000		15,052,000		15,020,000
Sale of common shares, net				$ 31,499,000
Share repurchase program, authorized amount						$ 50,000,000
Remaining authorized repurchase amount	$ 14,200,000		$ 14,200,000
Preferred shares of beneficial interest, shares outstanding (in shares) | shares	3,881,000		3,881,000		3,881,000
Preferred shares, liquidation preference (in dollars per share) | $ / shares	$ 25		$ 25		$ 25
Preferred units, shares issued (in shares) | shares	166,000		166,000		166,000
Preferred units, par value (in dollars per share) | $ / shares	$ 100		$ 100		$ 100
Preferred units, liquidation preference	$ 16,560,000		$ 16,560,000		$ 16,560,000
At-The-Market Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common shares, net	0	$ 0
Aggregate gross sales price of common shares, authorized amount	250,000,000		250,000,000
Aggregate gross sales price of common shares, remaining authorized amount	$ 126,600,000		$ 126,600,000
2015 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards issued (in shares) | shares	64	199	19,014	24,296
Sale of common shares, net	$ 5,000	$ 18,000	$ 1,700,000	$ 637,000
Series E Preferred Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred shares, shares issued (in shares) | shares	1,700,000		1,700,000		1,800,000
Preferred units, par value (in dollars per share) | $ / shares	$ 100		$ 100		$ 100
Preferred shares, dividend rate			0.03875%
Preferred units, conversion ratio	1.2048		1.2048
Preferred shares liquidation preference	$ 173,300,000		$ 173,300,000
Series C Preferred Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred shares, dividend rate			6.625%
Preferred shares liquidation preference	$ 97,000,000		$ 97,000,000
Preferred shares of beneficial interest, shares outstanding (in shares) | shares	3,900,000		3,900,000		3,900,000
Preferred shares, liquidation preference (in dollars per share) | $ / shares	$ 25.00		$ 25.00
Preferred shares, annual distribution accrual rate (in dollars per share) | $ / shares			$ 1.65625
Series D Preferred Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred units, shares issued (in shares) | shares	165,600		165,600		165,600
Preferred units, par value (in dollars per share) | $ / shares	$ 100		$ 100
Distribution rate			3.862%
Units converted, ratio	1.37931		1.37931
Preferred units, liquidation preference	$ 16,600,000		$ 16,600,000