CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 366,389	$ 169,075	$ 28,420
Adjustments to reconcile net income to net cash provided by operating activities:
Loss (gain) on early extinguishment of debt, net		1,588	(3,661)
(Gain) loss on remeasurement, sale or write down of assets, net	(204,668)	22,037	(497)
(Gain) loss on disposition of assets, net from discontinued operations	(74,833)	58,230	23
Depreciation and amortization	322,720	282,643	260,252
Amortization of net (premium) discount on mortgages, bank and other notes payable	(1,600)	9,060	2,940
Amortization of share and unit-based plans	12,324	12,288	14,832
Provision for doubtful accounts	3,329	3,212	4,361
Income tax benefit	(4,159)	(6,110)	(9,202)
Equity in income of unconsolidated joint ventures	(79,281)	(294,677)	(79,529)
Co-venture expense	6,523	5,806	6,193
Distributions of income from unconsolidated joint ventures	29,147	12,778	20,634
Changes in assets and liabilities, net of acquisitions and dispositions:
Tenant and other receivables	(9,252)	(8,049)	9,933
Other assets	(9,659)	(4,421)	(25,529)
Due from affiliates	(1,181)	3,106	(565)
Accounts payable and accrued expenses	13,430	(11,797)	(8,588)
Other accrued liabilities	(17,933)	(17,484)	(19,582)
Net cash provided by operating activities	351,296	237,285	200,435
Cash flows from investing activities:
Acquisition of properties	(1,061,851)	(125,105)
Development, redevelopment, expansion and renovation of properties	(142,210)	(58,932)	(137,803)
Property improvements	(45,654)	(62,974)	(47,986)
Redemption of redeemable non-controlling interests		(11,366)	(9,225)
Proceeds from note receivable			11,763
Issuance of notes receivable	(12,500)
Proceeds from maturities of marketable securities	1,378	1,362	1,316
Deposit on acquisition of property	(30,000)
Deferred leasing costs	(30,614)	(33,955)	(30,297)
Distributions from unconsolidated joint ventures	322,242	215,651	117,342
Contributions to unconsolidated joint ventures	(95,358)	(155,351)	(16,688)
Collections of/loans to unconsolidated joint ventures, net	650	(900)	(779)
Proceeds from sale of assets	136,707	16,960
Restricted cash	(6,164)	2,524	(29,815)
Net cash used in investing activities	(963,374)	(212,086)	(142,172)
Cash flows from financing activities:
Proceeds from mortgages, bank and other notes payable	3,193,451	757,000	927,514
Payments on mortgages, bank and other notes payable	(2,371,890)	(627,369)	(1,568,161)
Repurchase of convertible senior notes		(180,314)	(18,191)
Deferred financing costs	(15,108)	(18,976)	(10,856)
Proceeds from share and unit-based plans	1,263	1,032	902
Net proceeds from stock offerings	175,649		1,220,829
Exercise of stock warrants	(7,371)	(1,278)	(17,639)
Redemption of noncontrolling interests	(86)	(42)	(341)
Contributions from noncontrolling interests	379	4,204
Dividends and distributions	(326,185)	(296,948)	(225,958)
Distributions to co-venture partner	(39,479)	(40,905)	(13,972)
Net cash provided by (used in) financing activities	610,623	(403,596)	294,127
Net (decrease) increase in cash and cash equivalents	(1,455)	(378,397)	352,390
Cash and cash equivalents, beginning of year	67,248	445,645	93,255
Cash and cash equivalents, end of year	65,793	67,248	445,645
Supplemental cash flow information:
Cash payments for interest, net of amounts capitalized	181,971	175,902	211,830
Non-cash investing and financing activities:
Accrued development costs included in accounts payable and accrued expenses and other accrued liabilities	26,322	13,291	45,224
Mortgage notes payable settled in deed-in-lieu of foreclosure	185,000	38,968
Conversion of Operating Partnership Units to common stock	26,991	21,698	8,759
Acquisition of properties by assumption of mortgage note payable and other accrued liabilities	420,123	192,566
Acquisition of property by issuance of common stock	30,000
Property distributed from unconsolidated joint venture		445,004
Assumption of mortgage notes payable and other liabilities from unconsolidated joint ventures		240,537
Contribution of development rights from noncontrolling interests		74,717
Disposition of property in exchange for investments in unconsolidated joint ventures		56,952
Stock dividend			$ 43,086