CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 338,723	$ 396,133
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	324,749	315,743
Amortization of deferred financing costs	3,565	4,042
Amortization of debt discount	789	849
Loss on extinguishment of debt, net	509	1,039
Amortization of stock-based compensation	13,719	10,127
Equity in loss of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	10,131	3,143
Casualty and impairment gain, net	0	(58)
Abandonment of development pursuits	1,285	725
Cash flow hedge losses reclassified to earnings	3,079	3,213
Gain on sale of real estate assets	(35,665)	(105,524)
Increase in resident security deposits, prepaid expenses and other assets	(24,241)	(3,875)
Increase (decrease) in accrued expenses, other liabilities and accrued interest payable	1,624	(260)
Net cash provided by operating activities	638,267	625,297
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(560,385)	(604,540)
Acquisition of real estate assets, including partnership interest	(152,260)	0
Capital expenditures - existing real estate assets	(48,006)	(37,081)
Capital expenditures - non-real estate assets	(4,222)	(1,896)
Mortgage note receivable payments	7,562	7,421
Increase in payables for construction	168,034	299,226
Proceeds from sale of real estate, net of selling costs	0	58
Insurance proceeds for property damage claims	(507)	(2,291)
Mortgage note receivable lending	978	27,511
Distributions from unconsolidated real estate entities	0	2,013
Investments in unconsolidated real estate entities	(1,218)	(7,102)
Net cash used in investing activities	(590,024)	(316,681)
Cash flows from financing activities:
Issuance of common stock, net	206,193	833
Dividends paid	(415,295)	(399,070)
Repayments of mortgage notes payable, including prepayment penalties	(137,653)	(59,314)
Issuance of unsecured notes	449,803	299,442
Payment of deferred financing costs	(10,668)	(3,345)
Payment of finance lease obligation	(535)
Payment of finance lease obligation		(535)
(Payment) receipt for termination of forward interest rate swaps	(12,309)	12,598
Contribution from noncontrolling interest	337	0
Payments related to tax withholding for share-based compensation	(14,286)	(10,524)
Distributions to DownREIT partnership unitholders	(23)	(22)
Distributions to joint venture and profit-sharing partners	(227)	(208)
Preferred interest obligation redemption and dividends	(1,400)	(480)
Net cash provided by (used in) financing activities	63,937	(160,625)
Net increase in cash and cash equivalents	112,180	147,991
Cash and cash equivalents and restricted cash, beginning of period	217,864	201,906
Cash and cash equivalents and restricted cash, end of period	330,044	349,897
Cash paid during the period for interest, net of amount capitalized	88,948	95,204
Supplemental Cash Flow Information [Abstract]
Cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statements of Cash Flows	$ 217,864	$ 201,906