Impairment of Real Estate, Impairment of Unconsolidated Entities and Write-Off of Abandoned Development Projects (Details) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	$ 200,155,000	$ 30,200,000	$ 208,210,000	$ 30,660,000
LiveWork Las Vegas [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	112,838,000	0	112,838,000	0
Promenade Bolingbrook (Regional Mall) [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	54,194,000	0	54,194,000	0
Orchard Town Center (Regional Mall) [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	15,649,000	0	15,649,000	0
Building J at Illinois Science and Technology Park (Office Building) [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	17,474,000	0	17,474,000	0
Halle Building (Office Building) [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	0	30,200,000	0	30,200,000
Investment in triple net lease retail property [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	0	0	6,870,000	0
Other [Member]
Schedule of Impairment of Real Estate Included in Continuing Operations [Line Items]
Impairment of real estate	$ 0	$ 0	$ 1,185,000	$ 460,000