Property (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Impairment losses related to property	$ 2,600,000	$ 0	$ 3,800,000	$ 300,000
Gross proceeds from sale and disposition of property			44,800,000
Number of operating properties acquired			2
Palm Coast [Member]
Increase in property due to acquisiton of joint venture interest			32,800,000
Acquired Real Estate [Member]
Real estate property acquisition			42,900,000
New Development Additions [Member]
Real estate property acquisition			$ 5,900,000