Schedule III: Rollforward of Real Estate Assets and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation Of Carrying Amount Of Real Estate Investments RollForward [Line Items]
Balance at the beginning of period	$ 1,050,291	$ 1,025,234	$ 967,975
Less: Fully depreciated assets	(14)	(381)	(3,471)
Balance at the end of the period	1,062,208	1,050,291	1,025,234
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at the beginning of period	157,232	132,386	114,235
Real Estate Accumulated Depreciation, Depreciation Expense	27,655	25,227	21,622
Less: Fully depreciated assets	(14)	(381)	(3,471)
Balance at the end of the period	184,873	157,232	132,386
Land Improvements [Member]
Reconciliation Of Carrying Amount Of Real Estate Investments RollForward [Line Items]
Real Estate, Improvements	0	0	0
Building Improvements [Member]
Reconciliation Of Carrying Amount Of Real Estate Investments RollForward [Line Items]
Real Estate, Improvements	50,869	102,402	238,119
Construction in Progress [Member]
Reconciliation Of Carrying Amount Of Real Estate Investments RollForward [Line Items]
Real Estate, Improvements	$ (38,938)	$ (76,964)	$ (177,389)