Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Land	$ 1,048,685	$ 1,003,422
Buildings and improvements	6,284,851	5,890,498
Real estate assets, at cost, total	7,333,536	6,893,920
Accumulated depreciation	(1,978,690)	(1,738,862)
Net operating real estate assets	5,354,846	5,155,058
Properties under development, including land	491,120	527,596
Investments in joint ventures	33,698	36,429
Properties held for sale	0	27,143
Total real estate assets	5,879,664	5,746,226
Accounts receivable - affiliates	25,100	25,977
Other assets, net	116,260	111,962
Cash and cash equivalents	10,617	153,918
Restricted cash	5,971	5,898
Total assets	6,037,612	6,043,981
Liabilities
Unsecured notes payable	1,824,930	1,828,485
Secured notes payable	899,757	902,128
Accounts payable and accrued expenses	133,353	157,232
Accrued real estate taxes	45,223	39,149
Distributions payable	64,275	60,386
Other liabilities	97,814	100,058
Total liabilities	$ 3,065,352	$ 3,087,438
Commitments and contingencies (Note 13)
Non-qualified deferred compensation share awards	$ 79,364	$ 68,134
Equity
Common shares of beneficial interest; $0.01 par value per share; 175,000 shares authorized; 100,636 and 100,620 issued; 97,571 and 97,604 outstanding at December 31, 2015 and 2014, respectively	976	976
Additional paid-in capital	3,662,864	3,667,448
Distributions in excess of net income attributable to common shareholders	(458,577)	(453,777)
Treasury shares, at cost (10,703 and 10,975 common shares, at December 31, 2015 and 2014, respectively)	(386,793)	(396,626)
Accumulated other comprehensive loss	(1,913)	(2,419)
Total common equity	2,816,557	2,815,602
Non-controlling interests	76,339	72,807
Total equity	2,892,896	2,888,409
Total liabilities and equity	$ 6,037,612	$ 6,043,981