Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
REAL ESTATE ASSETS (Notes 3, 17, and 18):
Land and improvements	$ 612,714	$ 537,574
Buildings and improvements	3,335,026	2,830,310
Undeveloped land and construction in progress	809,654	430,806
Total real estate held for investment	4,757,394	3,798,690
Accumulated depreciation and amortization	(756,515)	(742,503)
Total real estate held for investment, net ($319,770 and $101,352 of VIE, Note 2)	4,000,879	3,056,187
REAL ESTATE ASSETS AND OTHER ASSETS HELD FOR SALE, NET (Note 17)	0	84,156
CASH AND CASH EQUIVALENTS	16,700	4,777
RESTRICTED CASH (Note 17)	247,544	358
MARKETABLE SECURITIES (Notes 13 and 16)	7,435	5,691
CURRENT RECEIVABLES, NET (Note 5)	9,220	8,395
DEFERRED RENT RECEIVABLES, NET (Note 5)	115,418	101,142
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 3 and 4)	189,968	155,522
DEFERRED FINANCING COSTS, NET (Notes 2 and 7)	18,971	18,368
PREPAID EXPENSES AND OTHER ASSETS, NET	9,949	12,199
TOTAL ASSETS	4,616,084	3,446,795
LIABILITIES:
Secured debt (Notes 3, 6, 7 and 16)	561,096	351,825
Exchangeable senior notes, net (Notes 6, 7 and 16)	163,944	306,892
Unsecured debt, net (Notes 6, 7 and 16)	1,130,895	980,569
Unsecured line of credit (Notes 6, 7 and 16)	185,000	182,000
Accounts payable, accrued expenses and other liabilities (Note 15)	154,734	81,713
Accrued distributions (Note 10)	28,924	22,692
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 4 and 8)	117,904	79,781
Rents received in advance and tenant security deposits	37,654	26,917
Liabilities and deferred revenue of real estate assets held for sale (Note 17)	0	13,286
Total liabilities	2,380,151	2,045,675
COMMITMENTS AND CONTINGENCIES (Note 15)
NONCONTROLLING INTEREST (Note 9):
7.45% Series A Cumulative Redeemable Preferred units of the Operating Partnership	0	73,638
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	0	0
Common stock, $.01 par value, 150,000,000 shares authorized, 74,926,981 and 58,819,717 shares issued and outstanding, respectively	749	588
Additional paid-in capital	2,126,005	1,448,997
Distributions in excess of earnings	(129,535)	(277,450)
Total stockholders' equity	2,189,630	1,293,717
Noncontrolling interest:
Common units of the Operating Partnership	46,303	33,765
Total equity	2,235,933	1,327,482
TOTAL LIABILITIES, NONCONTROLLING INTEREST AND EQUITY	4,616,084	3,446,795
Series E Cumulative Redeemable Preferred Stock [Member]
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	0	38,425
Series F Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	0	83,157
Series G Cumulative Redeemable Preferred Stock [Member]
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	96,155	0
Series H Cumulative Redeemable Preferred Stock [Member]
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Cumulative Redeemable Preferred stock	$ 96,256	$ 0