NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Redeemable noncontrolling interests in the Operating Partnership
Minimum holding period prior to redemption (in years)	1 year
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, beginning of year	$ 1,018,665
Mark-to-market adjustment to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(205,713)	$ 144,197
Conversion of OP Units/DownREIT Units to Common Stock	(7,830)
Net income/(loss) attributable o redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	313	2,057
Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(9,182)
Vesting of Long-Term Incentive Plan Units	23,018
Allocation of other comprehensive income/(loss)	(138)
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, end of year	819,133
Net income/(loss) attributable to noncontrolling interests	(10)	30
Maximum
Redeemable noncontrolling interests in the Operating Partnership
Net income/(loss) attributable to noncontrolling interests	$ (100)	$ (100)
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