Impairment of Real Estate, Impairment of Unconsolidated Entities, Write-Off of Abandoned Development Projects and Gain (Loss) on Early Extinguishment of Debt (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 235,000	$ 1,100,000	$ 5,070,000	$ 1,100,000
Portage Michigan Retail Property [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	0	0	3,435,000	0
Land Projects Mill Creek [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	0	450,000	1,400,000	450,000
Land Projects Gladden Farms [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	0	650,000	0	650,000
Other [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	235,000	0	235,000	0
Simi Valley Town Center (Regional Mall) [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate		$ 45,410,000		$ 45,410,000