Discontinued Operations and Gain (Loss) on Disposition of Rental Properties (Details)	3 Months Ended	9 Months Ended
	Oct. 31, 2010	Oct. 31, 2011 Rental	Oct. 31, 2010
101 San Fernando [Member]
Summary of rental properties included in discontinued operations
Location		San Jose, California
Square Feet / Number of units/Rooms		323
Period Disposed		Q2-2010
Period Status	Yes		Yes
Waterfront Station - East 4th & West 4th Buildings [Member]
Summary of rental properties included in discontinued operations
Location		Washington, D.C.
Square Feet / Number of units/Rooms		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
Square Feet / Number of units/Rooms		352
Period Disposed		Q1-2011
Period Status	Yes	Yes	Yes
Simi Valley Town Center [Member]
Summary of rental properties included in discontinued operations
Location		Simi Vally, California
Square Feet / Number of units/Rooms		612,000
Period Disposed		Q4-2010
Period Status	Yes		Yes
Investment in triple net lease property [Member]
Summary of rental properties included in discontinued operations
Location		Pueblo, Colorado
Square Feet / Number of units/Rooms		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 / Number of units/Rooms		294,000
Period Disposed		Q3-2010
Period Status	Yes		Yes