NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 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	$ (64,384)	$ 85,235	(247,374)	$ 222,405
Conversion of OP Units/DownREIT Units to Common Stock			(11,623)
Net income/(loss) attributable o redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	(1,990)	2,162	2,614	6,871
Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership			(25,836)
Vesting of Long-Term Incentive Plan Units			23,501
Allocation of other comprehensive income/(loss)	100	(100)	39
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, end of year	759,986		759,986
Net income/(loss) attributable to noncontrolling interests	15	40	24	97
Maximum
Redeemable noncontrolling interests in the Operating Partnership
Net income/(loss) attributable to noncontrolling interests	$ (100)	$ (100)	$ (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