Schedule III Notes to Schedule III (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Real Estate, Gross, Beginning	$ 2,774,947,000	$ 2,584,947,000	$ 2,605,288,000
Real Estate, Other Acquisitions	772,073,000	248,438,000	35,924,000
Real Estate, Cost of Real Estate Sold	(14,744,000)	(58,438,000)	(21,751,000)
Impairment of Real Estate	(431,000)	0	(34,514,000)
Real Estate, Gross, Ending	3,531,845,000	2,774,947,000	2,584,947,000
Real Estate Accumulated Depreciation, Beginning	222,921,000	183,949,000	146,289,000
Real Estate Accumulated Depreciation, Real Estate Sold	(3,010,000)	(2,071,000)	(3,143,000)
Real Estate Accumulated Depreciation, Depreciation Expense	50,710,000	41,043,000	40,803,000
Real Estate Accumulated Depreciation, Ending	270,621,000	222,921,000	183,949,000
Development in Process	60,322,000	26,699,000	5,634,000
Real Estate and Accumulated Depreciation [Line Items]
Secured Debt	23,171,000	24,269,000
Operating Lease [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate, Federal Income Tax Basis	3,399,631,000
Direct Financing Lease [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate, Federal Income Tax Basis	4,178,000
Mortgage Agreement-1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Secured Debt	6,952
Mortgage Agreement-2 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Secured Debt	$ 21,000