CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 618,432	$ 588,540
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	490,213	472,282
Amortization of deferred financing costs	5,458	6,066
Amortization of debt discount	1,186	1,259
Loss on extinguishment of debt, net	602	2,717
Amortization of stock-based compensation	20,810	15,617
Equity in loss of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	10,787	4,514
Casualty and impairment gain, net	0	(58)
Abandonment of development pursuits	1,080	725
Cash flow hedge losses reclassified to earnings	4,825	4,679
Gain on sale of real estate assets	(166,223)	(141,415)
Decrease in resident security deposits, prepaid expenses and other assets	(29,804)	(4,509)
Increase in accrued expenses, other liabilities and accrued interest payable	57,556	30,140
Net cash provided by operating activities	1,014,922	980,557
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(791,551)	(864,550)
Acquisition of real estate assets, including partnership interest	(286,804)	(84,088)
Capital expenditures - existing real estate assets	(92,825)	(59,950)
Capital expenditures - non-real estate assets	(4,223)	(2,142)
Mortgage note receivable payments	(3,390)	6,946
(Decrease) increase in payables for construction	421,735	466,187
Proceeds from sale of real estate, net of selling costs	0	58
Insurance proceeds for property damage claims	(565)	(2,880)
Mortgage note receivable lending	978	50,929
Distributions from unconsolidated real estate entities	694	2,013
Investments in unconsolidated real estate entities	(1,253)	(7,979)
Net cash used in investing activities	(757,204)	(495,456)
Cash flows from financing activities:
Issuance of common stock, net	207,789	1,224
Dividends paid	(627,467)	(602,152)
Proceeds from Unsecured Lines of Credit	0	56,000
Proceeds from Notes Payable	30,250	0
Repayments of mortgage notes payable, including prepayment penalties	(160,709)	(157,164)
Issuance of unsecured notes	449,804	299,442
Payment of deferred financing costs	(10,910)	(3,347)
(Payment) receipt for termination of forward interest rate swaps	(12,309)	12,598
Contribution from noncontrolling interest	455	0
Payments related to tax withholding for share-based compensation	(15,961)	(10,543)
Distributions to DownREIT partnership unitholders	(34)	(33)
Distributions to joint venture and profit-sharing partners	(336)	(321)
Preferred interest obligation redemption and dividends	(1,400)	(1,120)
Net cash used in financing activities	(140,828)	(405,416)
Net increase in cash and cash equivalents	116,890	79,685
Cash and cash equivalents and restricted cash, beginning of period	217,864	201,906
Cash and cash equivalents and restricted cash, end of period	334,754	281,591
Cash paid during the period for interest, net of amount capitalized	114,400	130,361
Supplemental Cash Flow Information [Abstract]
Cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statements of Cash Flows	$ 217,864	$ 201,906