Discontinued Operations and Gain (Loss) on Disposition of Rental Properties (Details 1)	12 Months Ended																																								3 Months Ended
	Jan. 31, 2013 Emerald Palms [Member] apartmentunit	Jan. 31, 2012 Emerald Palms [Member]	Jan. 31, 2011 Emerald Palms [Member]	Jan. 31, 2013 Southfield [Member] apartmentunit	Jan. 31, 2012 Southfield [Member]	Jan. 31, 2011 Southfield [Member]	Jan. 31, 2013 101 San Fernando [Member] apartmentunit	Jan. 31, 2012 101 San Fernando [Member]	Jan. 31, 2011 101 San Fernando [Member]	Jan. 31, 2013 Fairmont Plaza [Member] sqft	Jan. 31, 2012 Fairmont Plaza [Member]	Jan. 31, 2011 Fairmont Plaza [Member]	Jan. 31, 2013 White Oak Village [Member] sqft	Jan. 31, 2012 White Oak Village [Member]	Jan. 31, 2011 White Oak Village [Member]	Jan. 31, 2013 Quebec Square [Member] sqft	Jan. 31, 2012 Quebec Square [Member]	Jan. 31, 2011 Quebec Square [Member]	Jan. 31, 2013 Ritz-Carlton hotel [Member] room	Jan. 31, 2012 Ritz-Carlton hotel [Member]	Jan. 31, 2011 Ritz-Carlton hotel [Member]	Jan. 31, 2013 250 Huron [Member] sqft	Jan. 31, 2012 250 Huron [Member]	Jan. 31, 2011 250 Huron [Member]	Jan. 31, 2013 Waterfront Station - East 4th & West 4th Buildings [Member] sqft	Jan. 31, 2012 Waterfront Station - East 4th & West 4th Buildings [Member]	Jan. 31, 2011 Waterfront Station - East 4th & West 4th Buildings [Member]	Jan. 31, 2013 Charleston Marriott hotel [Member] room	Jan. 31, 2012 Charleston Marriott hotel [Member]	Jan. 31, 2011 Charleston Marriott hotel [Member]	Jan. 31, 2013 Simi Valley Town Center [Member] sqft	Jan. 31, 2012 Simi Valley Town Center [Member]	Jan. 31, 2011 Simi Valley Town Center [Member]	Jan. 31, 2013 Saddle Rock Village [Member] sqft	Jan. 31, 2012 Saddle Rock Village [Member]	Jan. 31, 2011 Saddle Rock Village [Member]	Jan. 31, 2013 Six triple net lease properties [Member] sqft		Jan. 31, 2012 Six triple net lease properties [Member]	Jan. 31, 2011 Six triple net lease properties [Member]	Oct. 31, 2012 Three triple net lease properties [Member] property	Jul. 31, 2012 Two triple net lease properties [Member] property	Jan. 31, 2011 Triple net lease properties [Member] property
Summary of rental properties included in discontinued operations
Location	Miami, Florida			Whitemarsh, Maryland			San Jose, California			San Jose, California			Richmond, Virginia			Denver, Colorado			Cleveland, Ohio			Cleveland, Ohio			Washington, D.C.			Charleston, West Virginia			Simi Valley, California			Aurora, Colorado			Various
Number of Units/Rooms	505			212			323												206									352
Square Feet										335,000			843,000			739,000						119,000			631,000						612,000			294,000			487,000
Period Disposed	Q4-2012			Q3-2012			Q2-2010			Q4-2012			Q3-2012			Q1-2012			Q4-2011			Q4-2011			Q2-2011			Q1-2011			Q4-2010			Q3-2010			Various	[1]
Period Status	Yes	Yes	Yes	Yes	Yes	Yes	0	0	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	0	Yes	Yes	0	Yes	Yes	0	Yes	Yes	0	Yes	Yes	0	0	Yes	0	0	Yes	Yes		Yes	Yes
Number of triple net lease properties disposed of																																									3	2	1

[1] Includes three triple net lease properties disposed of during Q3-2012, two triple net lease properties disposed of during Q2-2012 and one triple net lease property disposed of during Q4-2010.