NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling interests
Minimum holding period prior to redemption (in years)	1 year
Redeemable noncontrolling interests in the Operating Partnership
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, beginning of year	$ 972,740	$ 948,138
Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	183,884	43,552	$ 71,096
Conversion of OP Units/DownREIT Units to Common Stock	134,031	13,328
Net income/(loss) attributable to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	14,426	18,215	10,933
Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(32,270)	(32,798)
OP Units Issued		4,320
Vesting of Long-Term Incentive Plan Units	14,742	4,397
Allocation of other comprehensive income/(loss)	(826)	244
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, end of year	1,018,665	972,740	948,138
Net income/(loss) attributable to noncontrolling interests	(125)	(175)	(147)
Net (income)/loss attributable to noncontrolling interests	$ (188)	$ (221)	$ (164)
LTIP Units | Minimum
Redeemable noncontrolling interests in the Operating Partnership
Vesting period	1 year
LTIP Units | Maximum
Redeemable noncontrolling interests in the Operating Partnership
Vesting period	3 years