Consolidated Balance Sheets (USD $)	Dec. 31, 2012	Dec. 31, 2011
Investment in real estate:
Land	$ 1,019,581,000	$ 1,018,521,000
Land improvements	2,624,218,000	2,591,225,000
Buildings and other depreciable property	527,718,000	470,403,000
Real Estate Investment Property, at Cost, Total	4,171,517,000	4,080,149,000
Accumulated depreciation	(963,657,000)	(813,926,000)
Net investment in real estate	3,207,860,000	3,266,223,000
Cash	37,140,000	70,460,000
Cash and cash equivalents	37,140,000	70,460,000
Notes receivable, net	53,172,000	64,239,000
Investment in joint ventures	8,420,000	8,557,000
Rents and other customer receivables, net	1,206,000	1,155,000
Deferred financing costs, net	20,696,000	23,039,000
Inventory	1,569,000	2,172,000
Deferred commission expense	22,842,000	19,687,000
Escrow deposits and other assets	45,321,000	40,569,000
Total Assets	3,398,226,000	3,496,101,000
Liabilities:
Mortgage notes payable	2,069,866,000	2,084,683,000
Term loan	200,000,000	200,000,000
Unsecured lines of credit	0	0
Accrued payroll and other operating expenses	63,736,000	62,062,000
Deferred revenue-upfront payments from right-to-use contracts	62,979,000	56,285,000
Deferred revenue-right-to-use annual payments	11,088,000	11,877,000
Accrued interest payable	10,548,000	10,737,000
Rents and other customer payments received in advance and security deposits	55,707,000	54,234,000
Distributions payable	0	16,943,000
Total Liabilities	2,473,924,000	2,496,821,000
Stockholders' Equity:
Preferred stock, $.01 par value 2,000,000 shares authorized; none issued and outstanding as of December 31, 2011 and 2010	0	0
Common stock, $.01 par value 100,000,000 shares authorized for 2011 and 2010; 41,078,200 and 30,972,353 shares issued and outstanding for 2011 and 2010, respectively	416,000	412,000
Paid-in capital	1,012,930,000	998,483,000
Distributions in excess of accumulated earnings	(287,652,000)	(270,021,000)
Accumulated other comprehensive loss	(2,590,000)	(2,547,000)
Total Stockholders' Equity	859,248,000	726,327,000
Non-controlling interests-Common OP Units	65,054,000	72,953,000
Total Equity	924,302,000	799,280,000
Total Liabilities and Equity	3,398,226,000	3,496,101,000
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, $0.01 par value, 8,000,000 shares authorized, issued and outstanding as of December 31, 2011, at liquidation value	0	200,000,000
Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Domain]
Stockholders' Equity:
Preferred stock, $.01 par value 2,000,000 shares authorized; none issued and outstanding as of December 31, 2011 and 2010	$ 136,144,000	$ 0