CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 786,103	$ 974,175	$ 876,660
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	661,578	631,196	584,150
Amortization of deferred financing costs	7,346	7,939	7,657
Amortization of debt discount	1,591	1,701	(5,915)
Loss on extinguishment of debt, net	602	17,492	25,472
Amortization of stock-based compensation	25,621	20,280	17,920
Equity in loss (income) of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	12,278	6,583	(19,798)
Casualty and impairment gain, net	0	826	8,568
Abandonment of development pursuits	2,943	501	388
Cash flow hedge losses reclassified to earnings	6,571	6,143	7,070
Gain on sale of real estate assets	(172,332)	(385,976)	(281,745)
(Increase) decrease in resident security deposits, prepaid expenses and other assets	(19,118)	12,583	9,382
Increase in accrued expenses, other liabilities and accrued interest payable	8,621	7,668	26,448
Net cash provided by operating activities	1,321,804	1,301,111	1,256,257
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(1,052,011)	(1,139,954)	(979,947)
Acquisition of real estate assets, including partnership interest	(420,517)	(338,620)	(462,317)
Capital expenditures - existing real estate assets	(135,626)	(83,607)	(65,181)
Capital expenditures - non-real estate assets	(5,266)	(3,325)	(8,809)
(Decrease) increase in payables for construction	(4,848)	11,606	(15,621)
Proceeds from sale of real estate, net of selling costs	422,041	883,313	503,039
Insurance proceeds for property damage claims	0	0	16,233
Mortgage note receivable lending	(692)	(3,699)	(17,590)
Mortgage note receivable payments	2,779	53,136	0
Distributions from unconsolidated real estate entities	10,454	35,516	89,305
Investments in unconsolidated real estate entities	(10,183)	(11,017)	(24,493)
Net cash used in investing activities	(1,193,869)	(596,651)	(965,381)
Cash flows from financing activities:
Issuance of common stock, net	409,725	52,261	111,093
Dividends paid	(839,646)	(805,239)	(772,657)
Issuance of mortgage notes payable	30,250	295,939	206,800
Repayments of mortgage notes payable, including prepayment penalties	(227,570)	(255,452)	(1,313,025)
Issuance of unsecured notes	449,804	299,442	1,696,826
Repayment of unsecured notes, including prepayment penalties	0	(258,579)	(300,000)
Payment of deferred financing costs	(10,909)	(16,258)	(17,552)
Finance Lease, Principal Payments	0	1,070	18,951
(Payment) receipt for termination of forward interest rate swaps	(12,309)	12,598	391
Proceeds from Noncontrolling Interests	456
Payments related to tax withholding for share-based compensation	(16,101)	(10,556)	(10,450)
Distributions to DownREIT partnership unitholders	(46)	(44)	(42)
Contributions from joint venture and profit-sharing partners	0	0	1,038
Distributions to joint venture and profit-sharing partners	(439)	(424)	(418)
Preferred interest obligation redemption and dividends	(1,400)	(1,120)	(2,000)
Net cash used in financing activities	(218,185)	(688,502)	(418,947)
Net (decrease) increase in cash and cash equivalents	(90,250)	15,958	(128,071)
Cash and cash equivalents and restricted cash, beginning of year	217,864	201,906	329,977
Cash and cash equivalents and restricted cash, end of year	127,614	217,864	201,906
Cash paid during the year for interest, net of amount capitalized	187,570	201,659	207,842
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents and restricted cash, end of year	$ 217,864	$ 217,864	$ 329,977