CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Net income	$ 73,728	$ 123,432
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	124,154	113,250
Depreciation expense from discontinued operations	65	324
Amortization of deferred financing costs and debt premium/discount	3,485	3,908
Amortization of stock-based compensation	3,262	3,409
Equity in (income) loss of unconsolidated entities and noncontrolling interests, net of eliminations	421	120
Gain on sale of real estate assets	(7,675)	(72,220)
Expensed acquisition costs	958
(Increase) decrease in cash in operating escrows	(1,144)	1,185
(Increase) decrease in resident security deposits, prepaid expenses and other assets	(9,943)	3,009
Increase (decrease) in accrued expenses, other liabilities and accrued interest payable	18,568	(4,693)
Net cash provided by operating activities	205,879	171,724
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(266,374)	(233,994)
Acquisition of real estate assets	(46,275)
Capital expenditures - existing real estate assets	(7,765)	(4,872)
Capital expenditures - non-real estate assets	(7,748)	(524)
Proceeds from exchange/sale of real estate, net of selling costs	22,371	187,587
Decrease in payables for construction	(612)	(6,180)
Decrease in cash in construction escrows	10,917	21,224
Decrease in investments in unconsolidated real estate entities	2,458	2,781
Net cash used in investing activities	(293,028)	(33,978)
Cash flows from financing activities:
Issuance of common stock	264,134	306,817
Dividends paid	(154,382)	(146,258)
Repayments of mortgage notes payable	(31,963)	(27,930)
Payment of deferred financing costs	(252)	(2,218)
Acquisition of joint venture partner equity interest	(6,570)
Distributions to DownREIT partnership unitholders	(13)	(27)
Distributions to joint venture and profit-sharing partners	(127)	(100)
Net cash provided by financing activities	70,827	130,284
Net (decrease) increase in cash and cash equivalents	(16,322)	268,030
Cash and cash equivalents, beginning of period	306,426	105,691
Cash and cash equivalents, end of period	290,104	373,721
Cash paid during the period for interest, net of amount capitalized	$ 76,315	$ 78,009