CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 100,681	$ 301,178
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	457,837	183,688
Depreciation expense from discontinued operations	10,727	10,641
Amortization of deferred financing costs and debt (premium) discount	(15,831)	4,122
Amortization of stock-based compensation	8,720	8,548
Equity in (income) loss of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	45,215	(7,484)
Cash flow hedge losses reclassified to earnings	57,913
Loss on extinguishment of debt, net		1,781
Gain on sale of real estate assets	(118,413)	(95,329)
Gain on sale of joint venture real estate assets	(12,667)
Gain on acquisition of unconsolidated entity		(14,194)
(Increase) decrease in cash in operating escrows	(12,883)	6,644
Increase in resident security deposits, prepaid expenses and other assets	(66,709)	(8,069)
Increase (decrease) in accrued expenses, other liabilities and accrued interest payable	15,333	(16,353)
Net cash provided by operating activities	469,923	375,173
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(908,215)	(567,867)
Acquisition of real estate assets, including partnership interest	(749,275)	(105,904)
Capital expenditures - existing real estate assets	(10,527)	(13,449)
Capital expenditures - non-real estate assets	(7,286)	(1,094)
Proceeds from sale of real estate, net of selling costs	432,380	182,225
Increase in payables for construction	31,124	14,419
Decrease in cash in construction escrows		16,944
Decrease (increase) in investments in unconsolidated real estate entities	16,788	(8,006)
Net cash used in investing activities	(1,195,011)	(482,732)
Cash flows from financing activities:
Issuance of common stock	2,874	326,653
Dividends paid	(387,658)	(270,866)
Issuance of mortgage notes payable	71,210
Repayments of mortgage notes payable, including prepayment penalties	(1,789,399)	(106,255)
Issuance of unsecured notes	400,000	450,000
Settlement of interest rate contract	(51,000)	(54,930)
Repayment of unsecured notes	(100,000)	(179,400)
Payment of deferred financing costs and issuance discounts	(6,093)	(6,744)
Acquisition of joint venture partner equity interest	(1,965)	(3,350)
Redemption of preferred interest obligation	(33,327)
Distributions to DownREIT partnership unitholders	(24)	(22)
Distributions to joint venture and profit-sharing partners	(238)	(247)
Net cash (used in) provided by financing activities	(1,895,620)	154,839
Net (decrease) increase in cash and cash equivalents	(2,620,708)	47,280
Cash and cash equivalents, beginning of period	2,733,618	616,853
Cash and cash equivalents, end of period	112,910	664,133
Cash paid during the period for interest, net of amount capitalized	$ 137,081	$ 101,121