Impairment of Real Estate, Impairment of Unconsolidated Entities, Write-Off of Abandoned Development Projects and Gain (Loss) on Extinguishment of Debt (Details) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 119,324,000	$ 4,763,000	$ 8,907,000
Land held for divestiture [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	115,654,000
Investment in triple net lease retail property [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	3,435,000		3,552,000
Gladden Farms (Land Project) [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate		650,000	2,985,000
Development Property at Waterfront Station [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate		3,103,000
Other [Member]
Schedule of Impairment of Real Estate [Line Items]
Impairment of real estate	$ 235,000	$ 1,010,000	$ 2,370,000