NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	$ 22,723	$ (7,027)	(182,990)	$ 137,170
Conversion of OP Units/DownREIT Units to Common Stock			(11,250)
Net income/(loss) attributable o redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership	4,291	2,652	4,604	4,709
Distributions to redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership			(17,511)
Vesting of Long-Term Incentive Plan Units			23,018
Allocation of other comprehensive income/(loss)	100	(400)	(70)
Redeemable noncontrolling interests in the Operating Partnership and DownREIT Partnership, end of year	834,466		834,466
Net income/(loss) attributable to noncontrolling interests	19	27	9	57
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