Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 89,950	$ 39,648
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of marketable securities	(521)	(4,543)
Gain on remeasurement of co-investment	(21,947)	0
Loss on early retirement of debt	2,661	820
Co-investments	5,141	3,963
Amortization expense	8,681	8,718
Amortization of discount on notes receivables	(1,373)	(1,316)
Amortization of discount on marketable securities	(3,808)	(3,492)
Gain on the sales of real estate	(10,870)	(5,051)
Depreciation	125,669	112,678
Equity-based compensation	2,880	1,618
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(3,653)	(1,720)
Accounts payable and accrued liabilities	26,167	18,205
Other liabilities	358	1,166
Net cash provided by operating activities	219,335	170,694
Additions to real estate:
Acquisitions of real estate	(157,011)	(43,328)
Improvements to recent acquisitions	(6,662)	(14,768)
Redevelopment	(31,277)	(26,929)
Revenue generating capital expenditures	(4,405)	(4,706)
Non-revenue generating capital expenditures	(15,776)	(13,946)
Acquisitions of and additions to real estate under development	(22,505)	(72,816)
Acquisition of membership interest in co-investment	(85,000)	0
Dispositions of real estate	27,800	15,972
Changes in restricted cash and refundable deposits	(13,370)	(1,165)
Purchases of marketable securities	(73,735)	(8,048)
Sales and maturities marketable securities	6,322	27,997
Collections of notes and other receivables	7,977	643
Contributions to co-investments	(158,769)	(121,450)
Distributions from co-investments	8,345	4,032
Net cash used in investing activities	(518,066)	(258,512)
Cash flows from financing activities:
Borrowings under debt agreements	1,347,973	872,041
Repayment of debt	(1,196,977)	(891,734)
Additions to deferred charges	(6,415)	(4,464)
Payment to settle derivative instruments	0	(2,395)
Net proceeds from issuance of Preferred stock, Series H	0	71,209
Retirement of Series B preferred units	0	(78,800)
Redemption of Series F preferred stock	0	(25,000)
Equity related issuance cost	(309)	(765)
Net proceeds from stock options exercised	2,169	6,714
Net proceeds from issuance of common stock	268,858	257,008
Contributions from noncontrolling interest	2,400	0
Distributions to noncontrolling interest	(12,875)	(13,295)
Redemption of noncontrolling interest	(1,595)	(4,644)
Common and preferred stock dividends paid	(115,444)	(102,790)
Net cash provided by financing activities	287,785	83,085
Net (decrease) increase in cash and cash equivalents	(10,946)	(4,733)
Cash and cash equivalents at beginning of year	12,889	13,753
Cash and cash equivalents at end of period	1,943	9,020
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $6.8 million, and $6.9 million capitalized in 2012 and 2011, respectively	68,555	66,629
Supplemental disclosure of noncash investing and financing activities:
Transfer from real estate under development to rental properties	5,648	86,995
Transfer from real estate under development to co-investments	148,053	54,472
Mortgage notes assumed in connection with purchases of real estate including the loan premiums recorded	71,340	20,927
Contribution of note receivable to co-investment	12,325	0
Change in accrual of dividends	4,766	2,610
Change in fair value of derivative liabilities	5,100	1,760
Change in fair value of marketable securities	4,542	398
Change in construction payable	2,239	1,566
Non cash contribution from noncontrolling interest	$ 0	$ 800