Properties, net (Details 3) (USD $)	3 Months Ended	9 Months Ended	1 Months Ended
	Jun. 30, 2011	Sep. 30, 2011 sqfeet Year property segment	Mar. 31, 2011 Fort Ritchie
Strategic Reallocation Plan and Impairment Losses
Term of Strategic Reallocation Plan (in years)		3
Aggregate non-cash impairment losses on properties to be disposed	$ 44,600,000
Non-cash impairment losses on properties to be disposed in discontinued operations	14,500,000	14,523,000
Income tax benefit of aggregate non-cash impairment losses on properties to be disposed	4,600,000
Expected net proceeds from Strategic Reallocation Plan		200,000,000
Properties
Non-cash impairment losses			$ 27,700,000