Impairment of Real Estate, Impairment of Unconsolidated Entities, Write-Off of Abandoned Development Projects and Gain (Loss) on Extinguishment of Debt (Details 1) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate	$ 119,324,000	$ 4,763,000	$ 8,907,000
Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate	10,257,000	81,643,000	27,394,000
250 Huron (Office Building) [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate	10,257,000	2,040,000
250 Huron (Office Building) [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate	10,257,000	2,040,000
Simi Valley Town Center (Regional Mall) [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate		76,962,000
Simi Valley Town Center (Regional Mall) [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate		76,962,000
Investment in triple net lease retail property [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate	3,435,000		3,552,000
Investment in triple net lease retail property [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate		2,641,000
Saddle Rock Village (Specialty Retail Center) [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate			13,179,000
Two Sterling Glen supported-living apartment communities [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate			9,775,000
101 San Fernando (Apartment Community) [Member] | Discontinued Operation [Member]
Schedule of Impairment of Real Estate Included in Discontinuing Operations [Line Items]
Impairment of real estate			$ 4,440,000