CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 352,771	$ 423,562	$ 441,370
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	560,215	243,680	226,728
Depreciation expense from discontinued operations	13,500	16,414	23,541
Amortization of deferred financing costs and debt (premium) discount	(22,947)	6,427	5,834
Amortization of stock-based compensation	15,160	8,707	7,244
Equity in loss (income) of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	33,125	(12,103)	2,246
Cash flow hedge losses reclassified to earnings	59,376	1,889
Casualty loss and impairment of real estate assets		1,449	14,052
Loss on extinguishment of debt, net	14,921	1,781	5,820
Gain on sale of real estate assets	(278,471)	(146,591)	(294,806)
Gain on acquisition of unconsolidated entity		(14,194)
(Increase) decrease in cash in operating escrows	(28,960)	6,543	(7,702)
(Increase) decrease in resident security deposits, prepaid expenses and other assets	(5,186)	7,992	(4,018)
Decrease (increase) in accrued expenses, other liabilities and accrued interest payable	10,997	(4,737)	9,045
Net cash provided by operating activities	724,501	540,819	429,354
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(1,285,715)	(755,363)	(640,778)
Acquisition of real estate assets, including partnership interest	(839,469)	(155,755)	(46,275)
Capital expenditures - existing real estate assets	(24,415)	(23,452)	(41,851)
Capital expenditures - non-real estate assets	(2,200)	(3,076)	(8,281)
Proceeds from exchange/sale of real estate, net of selling costs	919,682	274,018	310,228
Increase in payables for construction	34,779	16,832	2,342
Decrease in cash in construction escrows		16,824	14,109
Acquisition of mortgage note			(1,701)
Decrease (increase) in investments in unconsolidated real estate entities	16,164	6,586	(30,934)
Net cash used in investing activities	(1,181,174)	(623,386)	(443,141)
Cash flows from financing activities:
Issuance of common stock	4,703	2,430,190	1,049,835
Dividends paid	(526,050)	(365,572)	(318,231)
Issuance of mortgage notes payable	84,928
Repayments of mortgage notes payable, including prepayment penalties	(2,110,347)	(110,013)	(200,166)
Issuance of unsecured notes	750,000	700,000
Settlement of interest rate contract	(51,000)	(54,930)
Repayment of unsecured notes	(100,000)	(381,001)	(189,900)
Payment of deferred financing costs and issuance discounts	(10,100)	(15,664)	(5,996)
Redemption of units for cash by minority partners	(1,965)		(25)
Acquisition of joint venture partner equity interest		(3,350)	(9,070)
Distributions to DownREIT partnership unitholders	(32)	(29)	(20)
Distributions to joint venture and profit-sharing partners	(317)	(299)	(194)
Redemption of preferred interest obligation	(35,224)
Net cash (used in) provided by financing activities	(1,995,404)	2,199,332	326,233
Net (decrease) increase in cash and cash equivalents	(2,452,077)	2,116,765	312,446
Cash and cash equivalents, beginning of year	2,733,618	616,853	304,407
Cash and cash equivalents, end of year	281,541	2,733,618	616,853
Cash paid during the year for interest, net of amount capitalized	$ 179,325	$ 119,268	$ 156,898