Discontinued Operations and Gain on Disposition of Rental Properties (Details 3) (USD $)	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	$ 1,239,000	$ 19,299,000	$ 44,342,000	$ 28,178,000
Millender Center (Apartment Community) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	0	21,660,000	0
Southfield (Apartment Community) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	13,445,000	0	13,445,000
Sheraton Station Square (Hotel) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	0	18,096,000	0
Higbee Building (Office Building) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	0	2,922,000	0
Colorado Studios (Office Building) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	1,239,000	0	1,239,000	0
Triple net lease properties [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	6,568,000	222,000	6,568,000
Quebec Square (Specialty Retail Center) [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	0	0	0	8,879,000
Other [Member]
Gain (Loss) on Disposition of Rental Properties [Line Items]
Pre-tax gain on disposition of rental properties	$ 0	$ (714,000)	$ 203,000	$ (714,000)