Noncontrolling Interests on the Company's Consolidated Financial Statements (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Noncontrolling Interest (Textuals) [Abstract]
Percentage of general partnership interest owned by the company in the Operating Partnership	97.50%	96.80%	97.20%
Percentage of Common limited partnership interest owned by certain non-affiliated investors and certain directors and officers of the Company in the Operating Partnership	2.50%	3.20%	2.80%
Common units outstanding held by common limited partners	1,718,131	1,723,131	1,718,131
Conversion ratio of common units for common stock	1
Common stock, par value	$ 0.01		$ 0.01
Number of trading days	10
Aggregate value upon redemption of outstanding noncontrolling common units	$ 78,900,000		$ 64,700,000
Series A Cumulative Redeemable Preferred Unit [Member]
Temporary Equity [Line Items]
7.45% Series A cumulative redeemable preferred units of the Operating Partnership outstanding	1,500,000		1,500,000
Preferred units redemption value per unit	$ 50		$ 50
Changes to noncontrolling interest	$ 0	$ 0