Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net loss	$ (48,001)	$ (78,518)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	221,053	218,701
Amortization of above and below market leases, net	(1,315)	(733)
Amortization of debt premiums, discounts and financing costs	8,128	17,600
Straight-line rental income	(5,439)	(7,002)
Provision for asset impairment	27,887	58,175
(Gain) loss on sale of property	2,231	(1,210)
Loss on extinguishment of debt	1,398	0
Equity in earnings of unconsolidated entities	(2,517)	(5,435)
Distributions from unconsolidated entities	6,224	9,450
Impairment of investment in unconsolidated entities	4,200	0
Realized gain on securities	(877)	(6,891)
Impairment on investment in securities	1,899	0
Other non-cash adjustments	605	691
Changes in assets and liabilities:
Accounts and rents receivable	(3,768)	(6,891)
Deferred costs and other assets	4,638	(6,051)
Accounts payable and accrued expenses	23,537	(134)
Other liabilities	2,888	3,931
Net cash flows provided by operating activities	242,771	195,683
Cash flows from investing activities:
Purchase of investment properties	(211,020)	(65,544)
Acquired in-place and market lease intangibles, net	(5,863)	(5,355)
Capital expenditures and tenant improvements	(39,590)	(32,580)
Investment in development projects	(55,025)	(28,402)
Sale of investment properties	104,550	24,914
Purchase of marketable securities	(19,390)	(40,560)
Sale of marketable securities	10,793	28,134
Investment in unconsolidated entities	0	(331)
Distributions from unconsolidated entities	9,435	14,231
Payment of leasing fees	(3,455)	(4,093)
Payments from notes receivable	14	2,125
Restricted escrows and other assets	(940)	(6,811)
Other assets	0	(2,391)
Net cash flows used in investing activities	(210,491)	(116,663)
Cash flows from financing activities:
Proceeds from the distribution reinvestment program	97,571	99,960
Shares Repurchased	(24,185)	(5,000)
Distributions paid	(218,433)	(212,899)
Proceeds from mortgage debt and notes payable	404,508	309,756
Payoffs of mortgage debt	(303,343)	(281,319)
Principal payments of mortgage debt	(15,363)	(17,265)
Proceeds from margin securities debt, net	29,122	4,466
Payment of loan fees and deposits	(8,617)	(8,452)
Distributions paid to noncontrolling interests	(231)	(364)
Distributions paid to noncontrolling redeemable interests	0	(5,209)
Net cash flows used in financing activities	(38,971)	(116,326)
Net decrease in cash and cash equivalents	(6,691)	(37,306)
Cash and cash equivalents, at beginning of period	218,163	267,707
Cash and cash equivalents, at end of period	211,472	230,401
Supplemental disclosure of cash flow information:
Purchase of investment properties	(385,766)	(65,515)
Tenant and real estate tax liabilities assumed at acquisition, net	492	(29)
Assumption of mortgage debt at acquisition	180,000	0
Non-cash discount of mortgage debt assumed	(5,746)	0
Supplemental cash flow, total	(211,020)	(65,544)
Cash paid for interest, net capitalized interest of $5,601 and $5,186	132,094	143,972
Supplemental schedule of non-cash investing and financing activities:
Property acquired through exchange of notes receivable	0	20,000
Redemption value adjustment for noncontrolling redeemable interest	$ 0	$ 29,348