Impairment of Real Estate, Impairment of Unconsolidated Entities and Write-Off of Abandoned Development Projects (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012
Schedule of Impairment of Real Estate Included in Discontinued Operations [Line Items]
Impairment of real estate on discontinued operations	$ 0	$ 2,709	$ 0	$ 4,090
White Oak Village (Speciality Retail Center) [Member]
Schedule of Impairment of Real Estate Included in Discontinued Operations [Line Items]
Impairment of real estate on discontinued operations	0	1,566	0	1,566
Investment in triple net lease retail property [Member]
Schedule of Impairment of Real Estate Included in Discontinued Operations [Line Items]
Impairment of real estate on discontinued operations	0	882	0	2,263
Other [Member]
Schedule of Impairment of Real Estate Included in Discontinued Operations [Line Items]
Impairment of real estate on discontinued operations	$ 0	$ 261	$ 0	$ 261