Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
REAL ESTATE ASSETS:
Land and improvements	$ 838,927		$ 877,633
Buildings and improvements	3,880,883		4,059,639
Undeveloped land and construction in progress (Note 2)	1,265,659		1,120,660
Total real estate assets held for investment	5,985,469		6,057,932
Accumulated depreciation and amortization	(921,279)		(947,664)
Total real estate assets held for investment, net ($171,120 and $211,755 of VIE, respectively, Note 1)	5,064,190		5,110,268
REAL ESTATE ASSETS AND OTHER ASSETS HELD FOR SALE, NET (Note 3)	190,751		8,211
CASH AND CASH EQUIVALENTS	50,181		23,781
RESTRICTED CASH (Note 1)	8,287		75,185
MARKETABLE SECURITIES (Note 12)	13,337		11,971
CURRENT RECEIVABLES, NET (Note 5)	8,122	[1]	7,229	[1]
DEFERRED RENT RECEIVABLES, NET (Note 5)	168,581	[2]	156,416
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Note 4)	182,251		201,926
DEFERRED FINANCING COSTS, NET	17,346		18,374
PREPAID EXPENSES AND OTHER ASSETS, NET	22,434		20,375
TOTAL ASSETS	5,725,480		5,633,736
LIABILITIES:
Secured debt (Notes 6 and 12)	516,725	[3]	546,292	[3]
Unsecured debt, net (Notes 6 and 12)	1,783,280		1,783,121
Unsecured line of credit (Notes 6 and 12)	130,000		140,000
Accounts payable, accrued expenses and other liabilities	217,352		225,830
Accrued distributions (Note 15)	33,532		32,899
Deferred revenue and acquisition-related intangible liabilities, net (Note 4)	128,730		132,239
Rents received in advance and tenant security deposits	46,887		49,363
Liabilities of real estate assets held for sale (Note 3)	9,768		56
Total liabilities	2,866,274		2,909,800
COMMITMENTS AND CONTINGENCIES (Note 11)
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Common stock, $.01 par value, 150,000,000 shares authorized, 88,031,377 and 86,259,684 shares issued and outstanding, respectively	880		863
Additional paid-in capital	2,761,176		2,635,900
Distributions in excess of earnings	(154,355)		(162,964)
Total stockholders’ equity	2,800,112		2,666,210
Noncontrolling interest :
Common units of the Operating Partnership (Note 7)	53,232		51,864
Noncontrolling interest in consolidated subsidiary (Note 1)	5,862		5,862
Total noncontrolling interests	59,094		57,726
Total equity	2,859,206		2,723,936
TOTAL LIABILITIES AND EQUITY	5,725,480		5,633,736
Series G Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	96,155		96,155
Series H Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	$ 96,256		$ 96,256

[1] Excludes current receivables, net related to properties held for sale.

[2] Excludes deferred rent receivables, net related to properties held for sale as of March 31, 2015.

[3] Amounts reported include the amounts of unamortized debt premiums of $9.2 million and $10.3 million as of March 31, 2015 and December 31, 2014, respectively.