CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 141,599	$ 75,469
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	106,367	105,559
Depreciation expense from discontinued operations		4,270
Amortization of deferred financing costs	1,518	1,934
Amortization of debt premium/discount	(8,774)	(3,538)
Amortization of stock-based compensation	3,615	2,099
Equity in (income) loss of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	(547)	16,734
Cash flow hedge losses reclassified to earnings	1,573	1,391
Gain on sale of real estate assets	(37,869)	(84,491)
Decrease (increase) in cash in operating escrows	6,831	(6,758)
Decrease (increase) in resident security deposits, prepaid expenses and other assets	13,655	(23,299)
Decrease in accrued expenses, other liabilities and accrued interest payable	(7,651)	(7,982)
Net cash provided by operating activities	220,317	81,388
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(266,930)	(221,274)
Acquisition of real estate assets, including partnership interest		(749,275)
Capital expenditures - existing real estate assets	(13,709)	(1,852)
Capital expenditures - non-real estate assets	(9,300)	(1,764)
Proceeds from sale of real estate, net of selling costs	52,147	327,922
Decrease in payables for construction	(339)	(360)
Decrease (increase) in investments in unconsolidated real estate entities	13,767	(2,978)
Net cash used in investing activities	(224,364)	(649,581)
Cash flows from financing activities:
Issuance of common stock	7,234	253
Dividends paid	(138,393)	(110,891)
Repayments of mortgage notes payable, including prepayment penalties	(3,832)	(1,507,243)
Issuance of unsecured notes	250,000
Repayment of unsecured notes		(100,000)
Payment of deferred financing costs	(3,022)
Distributions to DownREIT partnership unitholders	(9)	(8)
Distributions to joint venture and profit-sharing partners	(82)	(80)
Redemption of preferred interest obligation	(3,200)
Net cash provided by (used in) financing activities	108,696	(1,717,969)
Net increase (decrease) in cash and cash equivalents	104,649	(2,286,162)
Cash and cash equivalents, beginning of period	281,541	2,733,618
Cash and cash equivalents, end of period	386,190	447,456
Cash paid during the period for interest, net of amount capitalized	$ 55,140	$ 45,765