Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Activities
Net income	$ 209,700	$ 677,122	$ 319,156
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	351,539	292,311	240,445
Equity in net income from unconsolidated joint ventures	(76,418)	(1,583)	(39,607)
Distributions of cumulative earnings from unconsolidated joint ventures	91,145	11,185	27,472
Equity in net gain on sale of interest in unconsolidated joint venture interest/ real estate	(37,053)	(2,918)	(128,921)
Purchase price fair value adjustment		(498,195)
Depreciable real estate reserves		5,789	2,750
Gain on sale of discontinued operations	(6,627)	(46,085)	(35,485)
Gain on sale of debt securities		(19,840)
Loan loss and other investment reserves, net of recoveries	564	6,722	17,751
Gain on sale of investment in marketable securities	(4,940)	(4,866)	(490)
(Gain) loss on early extinguishment of debt	6,978	(904)	1,900
Deferred rents receivable	(66,079)	(87,230)	(47,223)
Other non-cash adjustments	(15,229)	2,385	(749)
Changes in operating assets and liabilities:
Restricted cash - operations	(13,812)	(681)	4,513
Tenant and other receivables	(10,998)	(4,720)	271
Related party receivables	(3,529)	2,461	2,398
Deferred lease costs	(48,368)	(38,412)	(42,035)
Other assets	(35,932)	4,029	4,860
Accounts payable, accrued expenses and other liabilities	9,389	10,704	(3,706)
Deferred revenue and land leases payable	3,413	5,586	(2,242)
Net cash provided by operating activities	353,743	312,860	321,058
Investing Activities
Acquisitions of real estate property	(544,568)	(446,756)	(270,614)
Additions to land, buildings and improvements	(148,148)	(159,100)	(108,145)
Escrowed cash - capital improvements/acquisition deposits	(70,080)	29,281	(40,215)
Investments in unconsolidated joint ventures	(215,174)	(109,920)	(87,844)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	127,876	112,359	52,920
Net proceeds from disposition of real estate/joint venture interest	178,485	160,548	623,121
Other investments	(32,413)	12,186	32,607
Debt and preferred equity and other investments, net of repayments/participations	(466,371)	(338,195)	(183,015)
Net cash (used in) provided by investing activities	(1,170,393)	(739,597)	18,815
Financing Activities
Proceeds from mortgages and other loans payable	1,230,167	826,000	168,360
Repayments of mortgages and other loans payable	(688,065)	(765,378)	(149,832)
Proceeds from revolving credit facility and senior unsecured notes	1,751,480	1,901,068	670,992
Repayments of revolving credit facility and senior unsecured notes	(1,581,554)	(2,043,144)	(1,046,626)
Proceeds from stock options exercised and DRIP issuance	112,743	10,211	14,535
Net proceeds from sale of common stock	201,279	516,168
Net proceeds from sale of preferred stock	221,965		122,041
Redemption of preferred stock	(200,013)
Purchases of treasury stock	(14,150)	(5,486)
Distributions to noncontrolling interests in other partnerships	(21,946)	(143,578)	(13,489)
Contributions from noncontrolling interests in other partnerships	25,894		2,788
Redemption of noncontrolling interests in operating partnership			(13,012)
Distributions to noncontrolling interests in operating partnership	(3,296)	(727)	(511)
Dividends paid on common and preferred stock	(121,238)	(63,866)	(58,984)
Other obligations related to mortgage loan participations	5,000	35,850
Deferred loan costs and capitalized lease obligation	(49,824)	(35,019)	(47,020)
Net cash provided by (used in) financing activities	868,442	232,099	(350,758)
Net increase (decrease) in cash and cash equivalents	51,792	(194,638)	(10,885)
Cash and cash equivalents at beginning of period	138,192	332,830	343,715
Cash and cash equivalents at end of period	189,984	138,192	332,830
Supplemental cash flow disclosures
Interest paid	320,849	275,106	222,904
Income taxes paid	$ 17	$ 138	$ 1,041