Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets
Land	$ 483,198	$ 483,198
Income producing property	2,003,826	1,979,348
Real estate investment property, at cost	2,487,024	2,462,546
Accumulated depreciation and amortization	(646,993)	(604,614)
Net income producing property	1,840,031	1,857,932
Properties under development or held for future development	55,262	49,135
Total real estate held for investment, net	1,895,293	1,907,067
Investment in real estate sold or held for sale, net	0	11,528
Cash and cash equivalents	5,919	19,324
Restricted cash	10,839	14,582
Rents and other receivables, net of allowance for doubtful accounts of $9,585 and $10,958, respectively	60,100	57,076
Prepaid expenses and other assets	108,591	114,541
Other assets related to properties sold or held for sale	0	258
Total assets	2,080,742	2,124,376
Liabilities
Notes payable	846,450	906,190
Mortgage notes payable	312,211	342,970
Lines of credit	75,000	0
Accounts payable and other liabilities	51,715	52,823
Advance rents	14,239	16,096
Tenant security deposits	9,899	9,936
Other liabilities related to properties sold or held for sale	0	218
Total liabilities	1,309,514	1,328,233
Shareholders’ equity
Preferred shares; $0.01 par value; 10,000 shares authorized; no shares issued or outstanding	0	0
Shares of beneficial interest; $0.01 par value; 100,000 shares authorized: 66,500 and 66,437 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	665	664
Additional paid in capital	1,147,710	1,145,515
Distributions in excess of net income	(381,623)	(354,122)
Total shareholders’ equity	766,752	792,057
Noncontrolling interests in subsidiaries	4,476	4,086
Total equity	771,228	796,143
Total liabilities and equity	$ 2,080,742	$ 2,124,376