Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Real estate assets:
Land	$ 888,084	$ 851,303
Buildings and improvements	7,020,394	6,777,776
Real estate investment property, at cost	7,908,478	7,629,079
Accumulated depreciation	(1,873,310)	(1,762,149)
Real estate investment property, net, before developments in progress	6,035,168	5,866,930
Held-for-sale	0	14,033
Developments in progress	139,500	124,707
Net investment in real estate assets	6,174,668	6,005,670
Cash and cash equivalents	71,537	56,092
Receivables:
Tenant, net of allowance for doubtful accounts of $2,051 and $1,760 in 2012 and 2011, respectively	71,520	74,160
Other, net of allowance for doubtful accounts of $1,248 and $1,400 in 2012 and 2011, respectively	8,156	11,592
Mortgage and other notes receivable	25,442	34,239
Investments in unconsolidated affiliates	304,663	304,710
Intangible lease assets and other assets	257,625	232,965
Total assets	6,913,611	6,719,428
LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY
Mortgage and other indebtedness	4,693,208	4,489,355
Accounts payable and accrued liabilities	323,470	303,577
Total liabilities	5,016,678	4,792,932
Commitments and contingencies (Notes 5 and 11)
Redeemable noncontrolling interests:
Redeemable noncontrolling partnership interests	38,218	32,271
Redeemable noncontrolling preferred joint venture interest	423,777	423,834
Total redeemable noncontrolling interests	461,995	456,105
Preferred stock, $.01 par value, 15,000,000 shares authorized:
7.75% Series C Cumulative Redeemable Preferred Stock, 460,000 shares outstanding	5	5
7.375% Series D Cumulative Redeemable Preferred Stock, 1,815,000 shares outstanding	18	18
Common stock, $.01 par value, 350,000,000 shares authorized, 158,560,145 and 148,364,037 issued and outstanding in 2012 and 2011, respectively	1,586	1,484
Additional paid-in capital	1,697,943	1,657,927
Accumulated other comprehensive income	4,146	3,425
Dividends in excess of cumulative earnings	(432,908)	(399,581)
Total shareholders' equity	1,270,790	1,263,278
Noncontrolling interests	164,148	207,113
Total equity	1,434,938	1,470,391
Total Liabilities, Redeemable Noncontrolling Interests and Equity	$ 6,913,611	$ 6,719,428