CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 111,570	$ 214,430
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	305,280	124,137
Depreciation expense from discontinued operations	875	4,194
Amortization of deferred financing costs and debt (premium) discount	(8,390)	3,040
Amortization of stock-based compensation	3,581	4,268
Equity in (income) loss of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	33,134	(3,182)
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	(10,824)
Increase in cash in operating escrows	(8,291)	(1,988)
Increase in resident security deposits, prepaid expenses and other assets	(43,499)	(20,732)
(Increase) decrease in accrued expenses, other liabilities and accrued interest payable	2,188	(8,151)
Net cash provided by operating activities	267,211	222,468
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(591,894)	(341,144)
Acquisition of real estate assets, including partnership interest	(749,275)	(37,105)
Capital expenditures - existing real estate assets	(1,986)	(6,606)
Capital expenditures - non-real estate assets	(2,721)	(588)
Proceeds from sale of real estate, net of selling costs	432,380	182,225
Increase in payables for construction	31,307	6,582
Decrease in cash in construction escrows		1,697
(Increase) decrease in investments in unconsolidated real estate entities	(2,161)	2,188
Net cash used in investing activities	(884,350)	(192,751)
Cash flows from financing activities:
Issuance of common stock	2,605	175,682
Dividends paid	(249,267)	(177,322)
Net borrowings under unsecured credit facility	142,000
Issuance of mortgage notes payable	71,210
Repayments of mortgage notes payable, including prepayment penalties	(1,786,130)	(103,621)
Settlement of interest rate contract	(51,000)
Repayment of unsecured notes	(100,000)	(179,400)
Payment of deferred financing costs and issuance discounts	(524)	(123)
Acquisition of joint venture partner equity interest	(1,965)	(3,350)
Redemption of preferred interest obligation	(32,086)
Distributions to DownREIT partnership unitholders	(16)	(15)
Distributions to joint venture and profit-sharing partners	(159)	(158)
Net cash used by financing activities	(2,005,332)	(288,307)
Net decrease in cash and cash equivalents	(2,622,471)	(258,590)
Cash and cash equivalents, beginning of period	2,733,618	616,853
Cash and cash equivalents, end of period	111,147	358,263
Cash paid during the period for interest, net of amount capitalized	$ 75,648	$ 62,012