Discontinued Operations and Gain (Loss) on Disposition of Rental Properties (Details)	12 Months Ended
	Jan. 31, 2012 Rental	Jan. 31, 2011	Jan. 31, 2010
101 San Fernando (Apartment Community) [Member]
Summary of rental properties included in discontinued operations
Location	San Jose, California
Number of units/Rooms	323
Period Disposed	Q2-2010
Period Status		Yes	Yes
Sterling Glen of Glen Cove [Member]
Summary of rental properties included in discontinued operations
Location	Glen Cove, New York
Number of units/Rooms	80
Period Disposed	Q3-2009
Period Status			Yes
Sterling Glen of Great Neck [Member]
Summary of rental properties included in discontinued operations
Location	Great Neck, New York
Number of units/Rooms	142
Period Disposed	Q3-2009
Period Status			Yes
250 Huron (Office Building) [Member]
Summary of rental properties included in discontinued operations
Location	Cleveland, Ohio
Square Feet	119,000
Period Disposed	Q4-2011
Period Status	Yes	Yes	Yes
Ritz Carlton [Member]
Summary of rental properties included in discontinued operations
Location	Cleveland, Ohio
Number of units/Rooms	206
Period Disposed	Q4-2011
Period Status	Yes	Yes	Yes
Waterfront Station - East 4th & West 4th Buildings [Member]
Summary of rental properties included in discontinued operations
Location	Washington, D.C.
Square Feet	631,000
Period Disposed	Q2-2011
Period Status	Yes	Yes	Yes
Charleston Marriott hotel [Member]
Summary of rental properties included in discontinued operations
Location	Charleston, West Virginia
Number of units/Rooms	352
Period Disposed	Q1-2011
Period Status	Yes	Yes	Yes
Simi Valley Town Center (Regional Mall) [Member]
Summary of rental properties included in discontinued operations
Location	Simi Vally, California
Square Feet	612,000
Period Disposed	Q4-2010
Period Status		Yes	Yes
Investment in triple net lease retail property [Member]
Summary of rental properties included in discontinued operations
Location	Pueblo, Colorado
Square Feet	203,000
Period Disposed	Q4-2010
Period Status		Yes	Yes
Saddle Rock Village [Member]
Summary of rental properties included in discontinued operations
Location	Aurora, Colorado
Square Feet	294,000
Period Disposed	Q3-2010
Period Status		Yes	Yes
Grand Avenue [Member]
Summary of rental properties included in discontinued operations
Location	Queens, New York
Square Feet	100,000
Period Disposed	Q1-2009
Period Status			Yes