CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 588,540	$ 639,174
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	472,282	427,050
Amortization of deferred financing costs	6,066	5,729
Amortization of debt discount (premium)	1,259	(6,254)
Loss on extinguishment of debt, net	2,717	24,162
Amortization of stock-based compensation	15,617	13,979
Equity in loss (income) of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	4,514	(21,627)
Casualty and impairment (gain) loss, net	(58)	8,568
Abandonment of development pursuits	725	388
Cash flow hedge losses reclassified to earnings	4,679	5,301
Gain on sale of real estate assets	(141,415)	(200,110)
Decrease (increase) in resident security deposits, prepaid expenses and other assets	16,691	(27,384)
Increase in accrued expenses, other liabilities and accrued interest payable	9,742	64,802
Net cash provided by operating activities	981,359	933,778
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(864,550)	(743,275)
Payments to Acquire Other Real Estate	(84,088)	(228,011)
Capital expenditures - existing real estate assets	(59,950)	(41,809)
Capital expenditures - non-real estate assets	(2,142)	(5,308)
Proceeds from sale of real estate, net of selling costs	466,187	336,542
Insurance proceeds for property damage claims	58	13,268
Mortgage note receivable lending	(2,880)	(14,244)
Mortgage note receivable payments	50,929	0
Increase (decrease) in payables for construction	6,946	(16,660)
Distributions from unconsolidated real estate entities	2,013	89,305
Investments in unconsolidated real estate entities	(7,979)	(14,560)
Net cash used in investing activities	(495,456)	(624,752)
Cash flows from financing activities:
Issuance of common stock, net	1,224	110,117
Dividends paid	(602,152)	(576,685)
Proceeds from Unsecured Lines of Credit	56,000	242,000
Proceeds from Notes Payable	0	185,100
Repayments of mortgage notes payable, including prepayment penalties	(157,164)	(1,289,234)
Issuance of unsecured notes	299,442	948,616
Payment of deferred financing costs	(3,347)	(11,743)
Payment of capital lease obligation	(802)	(18,683)
Receipts for termination of forward interest rate swaps	12,598	391
Payments related to tax withholding for share-based compensation	(10,543)	(10,460)
Distributions to DownREIT partnership unitholders	(33)	(32)
Contributions from joint venture and profit-sharing partners	0	1,038
Distributions to joint venture and profit-sharing partners	(321)	(317)
Preferred interest obligation redemption and dividends	(1,120)	(2,000)
Net cash used in financing activities	(406,218)	(421,892)
Net increase (decrease) in cash and cash equivalents	79,685	(112,866)
Cash and cash equivalents and restricted cash, beginning of period	201,906	329,977
Cash and cash equivalents and restricted cash, end of period	281,591	217,111
Cash paid during the period for interest, net of amount capitalized	130,361	124,585
Supplemental Cash Flow Information [Abstract]
Cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statements of Cash Flows	$ 201,906	$ 329,977